Ue and communication control method

ABSTRACT

According to one aspect of the present invention, a communication control method is provided that determines whether congestion control is to be continued in a destination PLMN in a case that a PLMN is changed during the application of congestion control and the PLMN before the change is a home PLMN. In a case that the PLMN is changed while a back-off timer received along with a cause value for the congestion control is running and the PLMN before the change is a home PLMN, it is determined whether to allow UE to transmit an SM request message in the destination, based on the presence or absence of an information element notified from the network.

TECHNICAL FIELD

This application relates to a UE and a communication control method.This application claims the benefit of priority to Japanese PatentApplication No. 2019-70076 filed on Apr. 1, 2019, which is incorporatedherein by reference in its entirety.

BACKGROUND ART

The 3rd Generation Partnership Project (3GPP), which undertakesactivities for standardizing recent mobile communication systems, hasstudied System Architecture Evolution (SAE) which is a systemarchitecture of Long Term Evolution (LTE). The 3GPP is in the process ofstandardizing Evolved Packet System (EPS) as a communication system forrealizing an all-Internet Protocol (IP) architecture. Note that a corenetwork constituting the EPS is called an Evolved Packet Core (EPC).

Additionally, the 3GPP recently has been studying a next-generationcommunication technology and a system architecture for 5th Generation(5G) mobile communication system which is a next-generation mobilecommunication system. Especially, as a system for achieving the 5Gmobile communication system, the 3GPP is in a process of standardizing5G System (5GS) (see NPL 1 and NPL 2). The 5GS extracts technical issuesassociated with connection of various terminals to a cellular networkand standardizes solutions.

Examples of the requirement include optimization and diversification ofa communication procedure to support a continual mobile communicationservice depending on terminals supporting various access networks, andoptimization of a system architecture suitable for the optimization anddiversification of the communication procedure.

CITATION LIST Non Patent Literature

NPL 1: 3GPP TS 23.501 v15.5.0; 3rd Generation Partnership Project;Technical Specification Group Services and System Aspects; SystemArchitecture for the 5G System, Stage 2 (Release 15)

NPL 2: 3GPP TS 23.502 v15.5.0; 3rd Generation Partnership Project;Technical Specification Group Services and System Aspects: Proceduresfor the 5G System; Stage 2 (Release 15)

NPL 3: 3GPP TS 24.501 v15.2.1; 3rd Generation Partnership Project;Technical Specification Group Core Network and Terminals;Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3 (Release15)

SUMMARY OF INVENTION Technical Problem

The 5GS has studied a mechanism that provides a function equivalent tocongestion control, and additionally, control signal management based oncauses other than congestion control (see NPL 1, NPL 2, and NPL 3).

However, in a state where the congestion control is applied, in a casethat UE changes a PLMN, and the PLMN before the change is a home PLMN,it is not clear whether the congestion control is continued in adestination PLMN to which the UE moves.

The present invention has been made in view of such circumstances, andan object of the present invention is to provide a mechanism and acommunication control method for implementing a control signalmanagement process based on causes for congestion control in a case ofchanging the system.

Solution to Problem

A UE according to the present invention is a User Equipment (UE)including a transmission and/or reception unit and a controller, whereinthe transmission and/or reception unit receives a Protocol Data Unit(PDU) session establishment reject message from a control apparatus in aProtocol Data Unit (PDU) session establishment procedure, the controllerstarts a back-off timer by using a back-off timer value in a case thatfirst information and the back-off timer value are included in the PDUsession establishment reject message and a combination of a certainpiece of Single Network Slice Selection Assistance information (S-NSSAI)and a Data Network Name (DNN) is provided during the PDU sessionestablishment procedure, the first information is a cause valueindicating that a resource for a specific slice and the DNN isinsufficient, in a case that the first information and secondidentification information are included in the PDU session establishmentreject message, the second identification information indicating thatthe back-off timer is applied to every Public Land Mobile Network(PLMN), the transmission and/or reception unit does not transmit anotherPDU session establishment request message or another PDU sessionmodification request message for the combination of the certain piece ofS-NSSAI and the DNN in every PLMN while the back-off timer is running,and in a case that the first information and the second identificationinformation are included in the PDU session establishment rejectmessage, the second identification information indicating that theback-off timer is applied in a registered PLMN, the transmission and/orreception unit does not transmit another PDU session establishmentrequest message or another PDU session modification request message forthe combination of the certain piece of S-NSSAI and the DNN in theregistered PLMN while the back-off timer is running.

A UE according to the present invention is a User Equipment (UE)including a transmission and/or reception unit and a controller, whereinthe transmission and/or reception unit receives a Protocol Data Unit(PDU) session establishment reject message from a control apparatus in aProtocol Data Unit (PDU) session establishment procedure, the controllerstarts a back-off timer by using a back-off timer value in a case thatfirst information and the back-off timer value are included in the PDUsession establishment reject message and a combination of a certainpiece of Single Network Slice Selection Assistance information (S-NSSAI)and a Data Network Name (DNN) is provided during the PDU sessionestablishment procedure, the first information is a cause valueindicating that a resource for a specific slice and the DNN isinsufficient, in a case that the first information and secondidentification information are included in the PDU session establishmentreject message, the second identification information indicating thatthe back-off timer is applied to every Public Land Mobile Network(PLMN), the controller does not transmit another PDU sessionestablishment request message or another PDU session modificationrequest message for the combination of the certain piece of S-NSSAI andthe DNN in every PLMN while the back-off timer is running, and in a casethat the first information and the second identification information areincluded in the PDU session establishment reject message, the secondidentification information indicating that the back-off timer is appliedin a registered PLMN, the controller does not transmit another PDUsession establishment request message or another PDU sessionmodification request message for the combination of the certain piece ofS-NSSAI and the DNN in the registered PLMN while the back-off timer isrunning.

A UE according to the present invention is a User Equipment (UE)including a transmission and/or reception unit and a controller, whereinthe transmission and/or reception unit receives a Protocol Data Unit(PDU) session establishment reject message from a control apparatus in aProtocol Data Unit (PDU) session establishment procedure, the controllerstarts a back-off timer by using a back-off timer value in a case thatfirst information and the back-off timer value are included in the PDUsession establishment reject message and a combination of a certainpiece of Single Network Slice Selection Assistance information (S-NSSAI)and a Data Network Name (DNN) is provided during the PDU sessionestablishment procedure, the first information is a cause valueindicating that a resource for a specific slice and the DNN isinsufficient, in a case that the first information and secondidentification information are included in the PDU session establishmentreject message, the second identification information indicating thatthe back-off timer is applied to every Public Land Mobile Network(PLMN), the controller configures the transmission and/or reception unitto not transmit another PDU session establishment request message oranother PDU session modification request message for the combination ofthe certain piece of S-NSSAI and the DNN in every PLMN while theback-off timer is running, and in a case that the first information andthe second identification information are included in the PDU sessionestablishment reject message, the second identification informationindicating that the back-off timer is applied in a registered PLMN, thetransmission and/or reception unit configures the transmission and/orreception unit to not transmit another PDU session establishment requestmessage or another PDU session modification request message for thecombination of the certain piece of S-NSSAI and the DNN in theregistered PLMN while the back-off timer is running.

Advantageous Effects of Invention

According to one aspect of the present invention, a terminal apparatusconstituting the 5GS and an apparatus in a core network perform amanagement process such as the congestion control for different systemsfor each terminal apparatus-initiated network slice and/or DNN.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an overview of a mobile communicationsystem.

FIG. 2 is a diagram illustrating an example of a configuration and thelike of access networks in the mobile communication system.

FIG. 3 is a diagram illustrating an example of a configuration or thelike of a core network_A in the mobile communication system.

FIG. 4 is a diagram illustrating an example of a configuration or thelike of a core network_B in the mobile communication system.

FIG. 5 is a diagram illustrating an apparatus configuration of a UE.

FIG. 6 is a diagram illustrating an apparatus configuration of an eNB/NRnode.

FIG. 7 is a diagram illustrating an apparatus configuration of anMME/AMF.

FIG. 8 is a diagram illustrating an apparatus configuration of anSMF/PGW/UPF.

FIG. 9 is a diagram illustrating an initial procedure.

FIG. 10 is a diagram illustrating a registration procedure.

FIG. 11 is a diagram illustrating a PDU session establishment procedure.

FIG. 12 is a diagram illustrating a network-initiated session managementprocedure.

DESCRIPTION OF EMBODIMENTS

A preferred embodiment for carrying out the present invention will bedescribed below with reference to the drawings. Note that, as anexample, an embodiment of a mobile communication system to which thepresent invention is applied will be described in the presentembodiment.

1. System Overview

An overview of a mobile communication system according to the presentembodiment will be described with reference to FIG. 1, FIG. 2, FIG. 3,and FIG. 4. FIG. 2 is a diagram for detailing access networks in themobile communication system of FIG. 1. FIG. 3 is a diagram for mainlydetailing a core network_A 90 in the mobile communication system ofFIG. 1. FIG. 4 is a diagram for mainly detailing a core network_B 190 inthe mobile communication system of FIG. 1. As illustrated in FIG. 1, amobile communication system 1 according to the present embodimentincludes a terminal apparatus (also referred to as a user apparatus or amobile terminal apparatus), a UE (User Equipment)_A 10, an AccessNetwork (AN)_A, an access network_B, a Core Network (CN)_A 90, a corenetwork_B 190, and a Packet Data Network (PDN)_A 6, and a Data Network(DN)_A 5. Note that a combination of the access network_A and the corenetwork_A 90 may be referred to as an Evolved Packet System (EPS) (4Gmobile communication system), a combination of the access network_B, thecore network_B 190, and the UE_A 10 may be referred to as the 5G System(5GS) (5G mobile communication system), or the configurations of the 5GSand the EPS need not necessarily be limited thereto. Note that, for thesake of simplicity, the core network_A 90, the core network_B 190, or acombination thereof may also be referred to as a core network, theaccess network_A, the access network_B, or a combination thereof mayalso be referred to as an access network or a radio access network, andthe DN_A 5, the PDN_A 6, or a combination thereof may also be referredto as a DN.

Here, the UE_A 10 may be an apparatus that can connect to a networkservice via 3GPP access (also referred to as 3GPP access or a 3GPPaccess network) and/or non-3GPP access (also referred to as non-3GPPaccess or a non-3GPP access network). In addition, the UE_A 10 may alsoinclude a Universal Integrated Circuit Card (UICC) and an embedded UICC(eUICC). Furthermore, the UE_A 10 may be a wirelessly connectableterminal apparatus and may be Mobile Equipment (ME), a Mobile Station(MS), a cellular Internet of Things (CIoT) terminal (CIoT UE), or thelike.

In addition, the UE_A 10 can be connected to an access network and/orcore network. In addition, the UE_A 10 can be connected to the DN_Aand/or the PDN_A via the access network and/or the core network. TheUE_A 10 transmits and/or receives (communicates) user data to and/orfrom the DN_A and/or the PDN_A by using a Protocol Data Unit or PacketData Unit (PDU) session and/or a Packet Data Network (PDN) connection(also referred to as a PDN connection). Furthermore, the communicationof the user data is not limited to Internet Protocol (IP) communication(IPv4 or IPv6), and may be, for example, non-IP communication in theEPS, or Ethernet communication (trade name) or Unstructuredcommunication in the 5GS.

Here, IP communication is data communication using IP, and is datacommunication achieved by transmitting and/or receiving an IP packetincluding an IP header. Note that a payload section constituting the IPpacket may include the user data transmitted and/or received by the UE_A10. Furthermore, non-IP communication is data communication withoutusing IP, and is data communication achieved by transmitting and/orreceiving data without IP header. For example, the non-IP communicationmay be the data communication achieved through transmitting and/orreceiving application data not given the IP address, or may transmitand/or receive the user data transmitted and/or received by the UE_A 10,the user data being given another header such as a MAC header and anEthernet (trade name) frame header.

Also, the PDU session is connectivity established between the UE_A 10and the DN_A 5 to provide a PDU connection service. To be more specific,the PDU session may be connectivity established between the UE_A 10 andan external gateway. Here, the external gateway may be a UPF, a PacketData Network Gateway (PGW), and the like. Furthermore, the PDU sessionmay be a communication path established to transmit and/or receive theuser data between the UE_A 10 and the core network and/or the DN, or acommunication path established to transmit and/or receive the PDU.Furthermore, the PDU session may be a session established between theUE_A 10 and the core network and/or the DN, or may be a logicalcommunication path including a transfer path such as one or more bearersbetween the apparatuses in the mobile communication system 1. To be morespecific, the PDU session may be a connection established by the UE_A 10between the core network_B 190 and/or the external gateway, or may be aconnection established between the UE_A 10 and the UPF. Furthermore, thePDU session may be connectivity and/or a connection between the UE_A 10and a UPF_A 235 via an NR node_A 122. Furthermore, the PDU session maybe identified by a PDU session ID and/or an EPS bearer ID.

Note that the UE_A 10 can transmit and/or receive the user data toand/or from an apparatus, such as an application server, that is locatedin the DN_A 5 by using the PDU session. In other words, the PDU sessioncan transfer the user data transmitted and/or received between the UE_A10 and the apparatus, such as the application server, that is located inthe DN_A 5. Furthermore, each apparatus (the UE_A 10, an apparatus inthe access network, and/or an apparatus in the core network and/or anapparatus in the data network) may correlate one or more pieces ofidentification information to the PDU session for management. Note thatthese pieces of identification information may include at least one ofan Access Point Name (APN), a Traffic Flow Template (TFT), a sessiontype, application identification information, identification informationof the DN_A 5, Network Slice Instance (NSI) identification information,Dedicated Core Network (DCN) identification information, and accessnetwork identification information, or may further include otherinformation. Furthermore, in a case that multiple PDU sessions areestablished, respective pieces of identification information correlatedto the PDU sessions may be the same contents or may be differentcontents. Furthermore, the NSI identification information is informationfor identifying an NSI, and hereinafter may be an NSI ID or a SliceInstance ID.

In addition, the access network_A and the access network_B may be any ofa Universal Terrestrial Radio Access Network (UTRAN)_A 20, an EvolvedUniversal Terrestrial Radio Access Network (E-UTRAN)_A 80, and a NG-RAN(5G-RAN)_A 120 as illustrated in FIG. 2. Note that hereinafter, theUTRAN_A 20 and/or E-UTRAN_A 80 and/or the NG-RAN_A 120 may be referredto as a 3GPP access or a 3GPP access network, and the wireless LANaccess network or the non-3GPP AN may be referred to as a non-3GPPaccess or a non-3GPP access network. Each radio access network includesan apparatus to which the UE_A 10 is actually connected (e.g., a basestation apparatus or an access point), and the like.

For example, the E-UTRAN_A 80 is an access network for Long TermEvolution (LTE) and configured to include one or more eNBs_A 45. TheeNB_A 45 is a radio base station to which the UE_A 10 connects throughEvolved Universal Terrestrial Radio Access (E-UTRA). Furthermore, in acase that multiple eNBs are present in the E-UTRAN_A 80, the multipleeNBs may be connected to each other.

Furthermore, the NG-RAN_A 120 is a 5G access network, may be a (R)ANillustrated in FIG. 4, and includes one or more New Radio AccessTechnology nodes (NR nodes)_A 122 and/or ng-eNBs. Note that the NRnode_A 122 is a radio base station to which the UE_A 10 connects withthe 5G radio access, and is also referred to as a gNB. Note that theng-eNB may be an eNB (E-UTRA) constituting a 5G access network, may beconnected to the core network_B 190 via the NR node_A, or may bedirectly connected to the core network_B 190. Also, in a case that thereare multiple NR nodes_A 122 and/or the ng-eNBs in the NG-RAN_A 120, eachof the NR nodes_A 122 and/or the ng-eNBs may be connected to oneanother.

Note that the NG-RAN_A 120 may be an access network configured in theE-UTRA and/or the 5G Radio Access. In other words, the NG-RAN_A 120 mayinclude the eNB_A 45, the NR node_A 122, or both the eNB_A 45 and the NRnode_A 122. In this case, the eNB_A 45 and the NR node_A 122 may besimilar apparatuses. Therefore, the NR node_A 122 can be substitutedwith the eNB_A 45.

The UTRAN_A 20 is an access network for the 3G mobile communicationsystem, and includes a Radio Network Controller (RNC)_A 24 and a Node B(NB)_A 22. The NB_A 22 is a radio base station to which the UE_A 10connects through Universal Terrestrial Radio Access (UTRA), and theUTRAN_A 20 may include one or multiple radio base stations. Furthermore,the RNC_A 24 is a controller for connecting the core network_A 90 andthe NB_A 22, and the UTRAN_A 20 may be configured to include one ormultiple RNCs. Moreover, the RNC_A 24 may be connected to one ormultiple NBs_A 22.

Note that, in the present specification, the expression “the UE_A 10 isconnected to each radio access network” is equivalent to “the UE_A 10 isconnected to a base station apparatus, an access point, or the likeincluded in each radio access network,” and is equivalent to“transmitted and/or received data, signals, and the like are alsotransferred through the base station apparatus and the access point”.Note that control messages transmitted and/or received between the UE_A10 and the core network_B 190 may be the same control message,regardless of a type of the access network. Therefore, the expression“the UE_A 10 and the core network_B 190 transmit and/or receive amessage to and/or from each other via the NR node_A 122” may beequivalent to “the UE_A 10 and the core network_B 190 transmit a messageto each other via the eNB_A 45”.

Furthermore, the access network is a radio network connecting with theUE_A 10 and/or the core network. The access network may be a 3GPP accessnetwork, or a non-3GPP access network. Note that the 3GPP access networkmay be the UTRAN_A 20, the E-UTRAN_A 80, and the NG-Radio Access Network(RAN)_A 120, and the non-3GPP access network may be the wireless LANaccess point (WLAN AN). Note that the UE_A 10 may connect to the accessnetwork or to the core network via the access network in order toconnect to the core network.

Moreover, the DN_A 5 and the PDN_A 6 are Data Networks that providecommunication services to the UE_A 10, may be configured as packet dataservice networks, and may be configured for each service. Furthermore,the DN_A 5 may include a connected communication terminal. Therefore,connecting with the DN_A 5 may be connecting with the communicationterminal or a server device located in the DN_A 5. Furthermore, thetransmission and/or reception of the user data to and/or from the DN_A 5may be transmission and/or reception of the user data to and/or from thecommunication terminal or server device located in the DN_A 5. Inaddition, although the DN_A 5 is outside the core networks in FIG. 1,the DN_A 5 may be within the core networks.

Furthermore, the core network_A 90 and/or the core network_B 190 may beconfigured as apparatuses in one or more core networks. Here, theapparatuses in the core networks may be apparatuses that perform part orall of processes or functions of apparatuses included in the corenetwork_A 90 and/or the core network_B 190. Note that the apparatuses inthe core network may be referred to as core network apparatuses.

Furthermore, the core network is an IP mobile communication network,operated by a Mobile Network Operator (MNO), that connects to the accessnetwork and/or the DN. The core network may be a core network for amobile communication operator that operates and manages the mobilecommunication system 1, or may be a core network for a virtual mobilecommunication operator such as a Mobile Virtual Network Operator (MVNO)and a Mobile Virtual Network Enabler (MVNE), or a virtual mobilecommunication service provider. Note that the core network_A 90 may bean Evolved Packet Core (EPC) constituting an Evolved Packet System(EPS), and the core network_B 190 may be a 5G Core Network (5GC)constituting a 5GS. Furthermore, the core network_B 190 may be a corenetwork for a system providing the 5G communication service. Conversely,the EPC may be the core network_A 90, and the 5GC may be the corenetwork_B 190. Note that the core network_A 90 and/or the core network_B190 is not limited to the above, and may be a network for providing amobile communication service.

Next, the core network_A 90 will be described. The core network_A 90 mayinclude at least one of a Home Subscriber Server (HSS)_A 50, anAuthentication Authorization Accounting (AAA), a Policy and ChargingRules Function (PCRF), the PGW_A 30, an ePDG, the SGW_A 35, the MobilityManagement Entity (MME)_A 40, a Serving GPRS Support Node (SGSN), and anSCEF. Furthermore, these may also be configured as Network Functions(NFs). The NF may be a processing function included in a network. Inaddition, the core network_A 90 is capable of connecting to multipleradio access networks (the UTRAN_A 20, the E-UTRAN_A 80).

Although only the HSS (HSS_A 50), the PGW (PGW_A 30), the SGW (SGW_A35), and the MME (MME_A 40) among the network elements are described inFIG. 3 for simplicity, it does not mean that no other apparatuses and/orNFs are included therein. Note that the UE_A 10 will also be referred toas UE, the HSS_A 50 as an HSS, the PGW_A 30 as a PGW, the SGW_A 35 as anSGW, the MMEA 40 as an MME, and the DN_A 5 and/or the PDN_A 6 as a DN ora PDN for simplicity.

The following briefly describes each apparatus included in the corenetwork_A 90.

The PGW_A 30 is a relay apparatus that is connected to the DN, the SGW_A35, the ePDG, the WLAN ANa 70, the PCRF, and the AAA, and transfers theuser data as a gateway between the DN (the DN_A 5 and/or the PDN_A 6)and the core network_A 90. Note that the PGW_A 30 may serve as a gatewayfor the IP communication and/or non-IP communication. Furthermore, thePGW_A 30 may have a function to transfer the IP communication, or mayhave a function to perform conversion between the non-IP communicationand the IP communication. Note that multiple gateways like this may bedeployed in the core network_A 90. Furthermore, the multiple gatewaysdeployed may serve as gateways for connecting the core network_A 90 witha single DN.

Note that a User Plane (U-Plane or UP) may be a communication path fortransmitting and/or receiving user data, and may include multiplebearers. Furthermore, a Control Plane (C-Plane or CP) may be acommunication path for transmitting and/or receiving a control message,and may include multiple bearers.

Further, the PGW_A 30 may be connected to the SGW, the DN, and a UserPlane Function (UPF) and/or a Session Management Function (SMF), or maybe connected to the UE_A 10 via the U-Plane. Furthermore, the PGW_A 30may be configured integrally with the UPF_A 235 and/or the SMF_A 230.

The SGW_A 35 is a relay apparatus that is connected to the PGW_A 30, theMME_A 40, the E-UTRAN_A 80, the SGSN, and the UTRAN_A 20, and transfersthe user data as a gateway between the core network_A 90 and the 3GPPaccess networks (the UTRAN_A 20, a GERAN, and the E-UTRAN_A 80).

The MME_A 40 is a control apparatus that is connected to the SGW_A 35,the access network, the HSS_A 50, and the SCEF, and performs locationinformation management including mobility management of the UE_A 10 viathe access network, and access control. Furthermore, the MME_A 40 mayinclude a function as a session management device to manage a sessionestablished by the UE_A 10. Multiple control apparatuses like this maybe deployed in the core network_A 90, and, for example, a locationmanagement apparatus different from the MME_A 40 may be configured. Likethe MME_A 40, the location management apparatus different from the MME_A40 may be connected to the SGW_A 35, the access network, the SCEF, andthe HSS_A 50. Furthermore, the MME_A 40 may be connected to an Accessand Mobility Management Function (AMF).

Furthermore, in a case that multiple MMEs are included in the corenetwork_A 90, the multiple MMEs may be connected to each other. Withthis configuration, a context of the UE_A 10 may be transmitted and/orreceived between the MMEs. In this way, the MME_A 40 is a managementapparatus to transmit and/or receive the control information related tothe mobility management and the session management to and/or from theUE_A 10. In other words, the MME_A 40 may be a control apparatus for aControl Plane (C-Plane; CP).

The example is described in which the MME_A 40 is configured to beincluded in the core network_A 90, but the MME_A 40 may be a managementapparatus configured in one or multiple core networks, DCNs, or NSIs, ormay be a management apparatus connected to one or multiple corenetworks, DCNs, or NSIs. Here, multiple DCNs or NSIs may be operated bya single network operator, or by different network operatorsrespectively.

The MME_A 40 may be a relay apparatus for transferring the user data asa gateway between the core network_A 90 and the access network. Notethat the user data transmitted and/or received by the MME_A 40 servingas a gateway may be small data.

Furthermore, the MME_A 40 may be an NF having a function of the mobilitymanagement of the UE_A 10 or the like, or an NF managing one or multipleNSIs. The MME_A 40 may be an NF having one or multiple of thesefunctions. Note that the NF may be one or multiple apparatuses deployedin the core network_A 90, a CP function (hereinafter, also referred toas a Control Plane Function (CPF) or a Control Plane Network Function)for the control information and/or control message, or a common CPfunction shared between multiple network slices.

Here, the NF is a processing function included in a network. That is,the NF may be a function apparatus such as an MME, an SGW, a PGW, a CPF,an AMF, an SMF, or a UPF, or may be a function such as mobilitymanagement (MM) and session management (SM), or capability information.The NF may be a function device to realize a single function, or afunction device to realize multiple functions. For example, an NF torealize the MM function and an NF to realize the SM function may beseparately present, or an NF to realize both the MM function and the SMfunction may be present.

The HSS_A 50 is a managing node that is connected to the MME_A 40, theAAA, and the SCEF, and manages subscriber information. The subscriberinformation of the HSS_A 50 is referred to during the access controlperformed by the MME_A 40, for example. Furthermore, the HSS_A 50 may beconnected to a location management device different from the MME_A 40.For example, the HSS_A 50 may be connected to the CPF_A 140.

Furthermore, the HSS_A 50, a Unified Data Management (UDM)_A 245 may beconfigured as different apparatuses and/or NFs or the same apparatusand/or NF.

The AAA is connected to the PGW 30, the HSS_A 50, the PCRF, and the WLANANa 70 and performs access control for the UE_A 10 connected via theWLAN ANa 70.

The PCRF is connected to the PGW_A 30, the WLAN ANa 75, the AAA, theDN_A 5 and/or the PDN_A 6 and performs QoS management on data delivery.For example, the PCRF manages QoS of a communication path between theUE_A 10, the DN_A 5, and/or the PDN_A 6. Furthermore, the PCRF may be anapparatus to create and/or manage a Policy and Charging Control (PCC)rule and/or a routing rule used by each apparatus for transmittingand/or receiving user data.

In addition, the PCRF may be a PCF to create and/or manage a policy.More specifically, the PCRF may be connected to the UPF_A 235.

The ePDG is connected to the PGW 30 and the WLAN ANb 75 and deliversuser data as a gateway between the core network_A 90 and the WLAN ANb75.

The SGSN is a control apparatus, connected to the UTRAN_A 20, the GERAN,and the SGW_A 35, for performing location management between the 3G/2Gaccess networks (UTRAN/GERAN) and the LTE (4G) access network (E-UTRAN).In addition, the SGSN has functions of selecting the PGW and the SGW,managing a time zone of the UE_A 10, and selecting the MME_A 40 at thetime of handover to the E-UTRAN.

The SCEF is a relay apparatus that is connected to the DN_A 5 and/or thePDN_A 6, the MME_A 40, and the HSS_A 50 and transfers the user data as agateway for connecting the DN_A 5 and/or the PDN_A 6 with the corenetwork_A 90. Note that the SCEF may serve as a gateway for non-IPcommunication. Furthermore, the SCEF may have a function to performconversion between non-IP communication and IP communication. Multiplegateways like this may be deployed in the core network_A 90.Furthermore, multiple gateways connecting the core network_A 90 with asingle DN_A 5 and/or PDN_A 6 and/or DN may be also deployed. Note thatthe SCEF may be outside or inside the core network.

Next, the core network_B 190 will be described. The core network_B 190may include at least one of an Authentication Server Function (AUSF), anAccess and Mobility Management Function (AMF)_A 240, an UnstructuredData Storage Network Function (UDSF), a Network Exposure Function (NEF),a Network Repository Function (NRF), a Policy Control Function (PCF), aSession Management Function (SMF)_A 230, a Unified Data Management(UDM), a User Plane Function (UPF)_A 235, an Application Function (AF),and a Non-3GPP InterWorking Function (N3IWF). Furthermore, these mayalso be configured as Network Functions (NFs). The NF may be aprocessing function included in a network.

Although only the AMF (AMF_A 240), the SMF (SMF_A 230), and the UPF(UPF_A 235) are illustrated in FIG. 4 among the above elements forsimplicity, it does not mean that no other elements (apparatuses and/orNetwork Functions (NFs)) are included therein. Note that the UE_A 10 isalso referred to as the UE, the AMF_A 240 as the AMF, the SMF_A 230 asthe SMF, the UPF_A 235 as the UPF, and the DN_A 5 as the DN forsimplicity.

In addition, FIG. 4 illustrates an N1 interface (hereinafter, alsoreferred to as a reference point), an N2 interface, an N3 interface, anN4 interface, an N6 interface, an N9 interface, and an N11 interface.Here, the N1 interface is an interface between the UE and the AMF, theN2 interface is an interface between the (R) access network (AN) and theAMF, and the N3 interface is an interface between the (R) access network(AN) and the UPF, the N4 interface is an interface between the SMF andthe UPF, the N6 interface is an interface between the UPF and the DN,the N9 interface is an interface between the UPF and the UPF, and the N1interface is an interface between the AMF and the SMF. These interfacescan be used to perform communication between the apparatuses. Here, the(R)AN is hereinafter also referred to as a NG RAN.

The following briefly describes each apparatus included in the corenetwork_B 190.

First, the AMF_A 240 is connected to another AMF, the SMF (SMF_A 230),the access network (i.e., the UTRAN_A 20, the E-UTRAN_A 80, the NG-RAN_A120), the UDM, the AUSF, and the PCF. The AMF_A 240 may play roles ofregistration management, connection management, reachability management,mobility management of the UE_A 10 or the like, transfer of a SessionManagement (SM) message between the UE and the SMF, accessauthentication or access authorization, a Security Anchor Function(SEA), Security Context Management (SCM), support for the N2 interfacefor the N3IWF, support for transmission and/or reception of NAS signalsto and/or from the UE via the N3IWF, authentication of the UE connectedvia the N3IWF, management of Registration Management (RM) states,management of Connection Management (CM) states, and the like. Inaddition, one or more AMFs_A 240 may be deployed within the corenetwork_B 190. In addition, the AMF_A 240 may be an NF that manages oneor more Network Slice Instances (NSI). In addition, the AMF_A 240 mayalso be a Common Control Plane Network Function (Common CPNF, or CCNF)shared among multiple NSIs.

Additionally, the RM state includes a deregistered state(RM-DEREGISTERED state) and a registered state (RM-REGISTERED state). Inthe RM-DEREGISTERED state, the UE is not registered in the network, andthus the AMF is not able to reach the UE because the UE context in theAMF does not have valid location information and routing information forthe UE. In the RM-REGISTERED state, the UE is registered in the network,and thus the UE can receive services that requires registration with thenetwork.

Additionally, the CM state includes a disconnected state (CM-IDLE state)and a connected state (CM-CONNECTED state). In the CM-IDLE state, the UEis in the RM-REGISTERED state but does not have a NAS signalingconnection established between the AMF and the UE via the N1 interface.Also, in the CM-IDLE state, the UE does not have an N2 interfaceconnection (N2 connection) and an N3 interface connection (N3connection). On the other hand, in the CM-CONNECTED state, the UE hasthe NAS signaling connection established between the AMF and the UE viathe N1 interface. Also, in the CM-CONNECTED state, the UE may have theN2 interface connection (N2 connection) and/or the N3 interfaceconnection (N3 connection).

The SMF_A 230 may have a function for Session Management (SM) of a PDUsession or the like, IP address allocation for the UE and a function formanagement thereof, a UPF selection and control function, a UPFconfiguration function for routing traffic to an appropriatedestination, a function for reporting arrival of downlink data (DownlinkData Notification), a function for providing SM information specific toan AN (for each AN) transmitted to the AN via the AMF through the N2interface, a function for determining a Session and Service Continuitymode (SSC mode) for a session, a roaming function, and the like. TheSMF_A 230 may be connected to the AMF_A 240, the UPF_A 235, the UDM, andthe PCF.

The UPF_A 235 is connected to the DN_A 5, the SMF_A 230, another UPF,and the access networks (i.e., the UTRAN_A 20, the E-UTRAN_A 80, and theNG-RAN_A 120). The UPF_A 235 may play roles of an anchor to intra-RATmobility or inter-RAT mobility, packet routing & forwarding, an uplinkclassifier (UL CL) function to support routing of multiple traffic flowsfor one DN, a branching point function to support a multi-homed PDUsession, QoS processing for a user plane, verification of uplinktraffic, buffering of downlink packets, a function of triggeringdownlink data notification, and the like. Furthermore, the UPF_A 235 maybe a relay apparatus that transfers the user data as a gateway betweenthe DN_A 5 and the core network_B 190. Note that the UPF_A 235 may serveas a gateway for IP communication and/or non-IP communication.Furthermore, the UPF_A 235 may have a function of transferring IPcommunication or a function to perform conversion between non-IPcommunication and IP communication. The multiple gateways deployed mayserve as gateways for connecting the core network_B 190 with a singleDN. Note that the UPF_A 235 may have connectivity with another NF or maybe connected to each apparatus via another NF.

Note that a UPF_C 239 (also referred to as a branching point or anuplink classifier) that is a UPF different from the UPF_A 235 may bepresent between the UPF_A 235 and the access network as an apparatus oran NF. In a case that the UPF_C 239 is present, the PDU session betweenthe UE_A 10 and the DN_A 5 is established via the access network, theUPF_C 239, and the UPF_A 235.

Additionally, the AUSF is connected to the UDM and the AMF_A 240. TheAUSF functions as an authentication server.

The UDSF provides a function for all NFs to store or retrieveinformation as unstructured data.

The NEF provides a means to securely provide services and capabilitiesprovided by the 3GPP network. The NEF stores information received fromanother NF as structured data.

In a case that a NF discovery request is received from a NF instance,the NRF provides the NF with information of found NF instances or holdsinformation of available NF instances or services supported by theinstances.

The PCF is connected to the SMF (the SMF_A 230), the AF, and the AMF_A240. The PCF provides a policy rule and the like.

The UDM is connected to the AMF_A 240, the SMF (SMF_A 230), the AUSF,and the PCF. The UDM includes a UDM FE (application front end) and aUser Data Repository (UDR).

The UDM FE performs processing of authentication information(credentials), location management, subscriber management (subscriptionmanagement), and the like. The UDR stores data necessary for the UDM FEfor provision and the policy profile necessary for the PCF.

The AF is connected to the PCF. The AF affects traffic routing or isinvolved in the policy control.

The N3IWF provides functions of establishing an IPsec tunnel with theUE, relaying NAS (N1) signaling between the UE and the AMF, processingN2 signaling transmitted from the SMF and relayed by the AMF,establishing IPsec Security Association (IPsec SA), relaying user planepackets between the UE and the UPF, selecting the AMF, and the like.

An S1 mode is a UE mode capable of transmitting and/or receivingmessages using an S1 interface. Note that the S1 interface may includean S1-MME interface, an S1-U interface, and an X2 interface connectingbetween the radio base stations.

The UE in the S1 mode can access the EPC via the eNB providing an E-UTRAfunction and access the EPC via an en-gNB providing an NR function, forexample.

Note that the access to the EPC via the eNB providing the E-UTRAfunction and the access to the EPC via the en-gNB providing the NRfunction are designated as the S1 modes, but may be configured asseparate and different modes.

An N1 mode is a UE mode in which the UE can access the 5GC via the 5Gaccess network. The N1 mode may be a UE mode capable of transmittingand/or receiving messages using the N1 interface. Note that the N1interface may include an Xn interface that connects between the N1interface and the radio base station.

The UE in the N1 mode can access the 5GC via the ng-eNB providing theE-UTRA function and access the 5GC via the gNB providing the NRfunction, for example.

Note that the access to the 5GC via the ng-eNB providing the E-UTRAfunction and the access to the 5GC via the gNB providing the NR functionare designated as the N1 modes, but may be configured as separate anddifferent modes.

1.2. Configuration of Each Apparatus

The configuration of each apparatus will be described below. Note thatsome or all of apparatuses to be described below and functions of unitsof the apparatuses may operate on physical hardware, or logical hardwarewhich is virtually configured on general-purpose hardware.

1.2.1. Configuration of UE

First, an example of an apparatus configuration of the UE_A 10 isillustrated in FIG. 5. As illustrated in FIG. 5, the UE_A 10 includes acontroller_A 500, a transmission and/or reception unit_A 520, and astorage unit_A 540. The transmission and/or reception unit_A 520 and thestorage unit_A 540 are connected to the controller_A 500 via a bus.Furthermore, an external antenna 410 is connected to the transmissionand/or reception unit_A 520.

The controller_A 500 is a function unit for controlling the entire UE_A10 and implements various processes of the entire UE_A 10 by reading outand performing various types of information and programs stored in thestorage unit_A 540.

The transmission and/or reception unit_A 520 is a function unit throughwhich the UE_A 10 connects to the base station (the UTRAN_A 20, theE-UTRAN_A 80, and the NG-RAN_A 120) and/or the wireless LAN access point(the WLAN AN) in the access network to connect to the access network. Inother words, the UE_A 10 can connect to the base station and/or theaccess point in the access network via the external antenna 410connected to the transmission and/or reception unit_A 520. To bespecific, the UE_A 10 can transmit and/or receive user data and/orcontrol information to and/or from the base station and/or the accesspoint in the access network via the external antenna 410 connected tothe transmission and/or reception unit_A 520.

The storage unit_A 540 is a function unit that stores programs, data,and the like necessary for each operation of the UE_A 10, and include,for example, a semiconductor memory, a Hard Disk Drive (HDD), a SolidState Drive (SSD), or the like. The storage unit_A 540 storesidentification information, control information, a flag, a parameter, arule, a policy, and the like included in a control message which istransmitted and/or received in the communication procedure describedbelow.

1.2.2. eNB/NR Node

Next, FIG. 6 illustrates an example of an apparatus configuration of theeNB_A 45 and the NR node_A 122. As illustrated in FIG. 6, the eNB_A 45and the NR node_A 122 include a controller_B 600, a network connectionunit_B 620, a transmission and/or reception unit_B 630, and a storageunit_B 640. The network connection unit_B 620, the transmission and/orreception unit_B 630, and the storage unit_B 640 are connected to thecontroller_B 600 via a bus. Furthermore, an external antenna 510 isconnected to the transmission and/or reception unit_B 630.

The controller_B 600 is a function unit for controlling the entire eNB_A45 and NR node_A 122, and implements various processes of the entireeNB_A 45 and NR node_A 122 by reading out and performing various typesof information and programs stored in the storage unit_B 640.

The network connection unit_B 620 is a function unit through which theeNB_A 45 and the NR node_A 122 connect to the AMF_A 240 and the UPF_A235 in the core network. In other words, the eNB_A 45 and the NR node_A122 can be connected to the AMF_A 240 and the UPF_A 235 in the corenetwork via the network connection unit_B 620. Specifically, the eNB_A45 and the NR node_A 122 can transmit and/or receive user data and/orcontrol information to and/or from the AMF_A 240 and/or the UPF_A 235via the network connection unit_B 620.

The transmission and/or reception unit_B 630 is a function unit throughwhich the eNB_A 45 and the NR node_A 122 connect to the UE_A 10. Inother words, the eNB_A 45 and the NR node_A 122 can transmit and/orreceive user data and/or control information to and/or from the UE_A 10via the transmission and/or reception unit_B 630.

The storage unit_B 640 is a function unit for storing programs, data,and the like necessary for each operation of the eNB_A 45 and the NRnode_A 122. The storage unit_B 640 includes, for example, asemiconductor memory, an HDD, an SSD, or the like. The storage unit_B640 stores identification information, control information, a flag, aparameter, and the like included in a control message which istransmitted and/or received in the communication procedure describedbelow. The storage unit_B 640 may store these pieces of information asthe contexts for each UE_A 10.

1.2.3. Configuration of MME/AMF

Next, FIG. 7 illustrates an example of an apparatus configuration of theMME_A 40 or the AMF_A 240. As illustrated in FIG. 7, the MME_A 40 or theAMF_A 240 include a controller_C 700, a network connection unit_C 720,and a storage unit_C 740. The network connection unit_C 720 and thestorage unit_C 740 are connected to the controller_C 700 via a bus.Furthermore, the storage unit_C 740 stores a context 642.

The controller_C 700 is a function unit for controlling the entire MME_A40 or AMF_A 240, and implements various processes of the entire AMF_A240 by reading out and performing various types of information andprograms stored in the storage unit_C 740.

The network connection unit_C 720 is a function unit through which theMME_A 40 or the AMF_A 240 connects to another MME_A 40 or AMF_240, theSMF_A 230, the base station (the UTRAN_A 20, the E-UTRAN_A 80, and theNG-RAN_A 120) and/or the wireless LAN access point (WLAN AN) in theaccess network, the UDM, the AUSF, and the PCF. In other words, theMME_A 40 or the AMF_A 240 can transmit and/or receive user data and/orcontrol information to and/or from the base station and/or access pointin the access network, the UDM, the AUSF, and the PCF via the networkconnection unit_C 720.

The storage unit_C 740 is a function unit for storing programs, data,and the like necessary for each operation of the MME_A 40 or the AMF_A240. The storage unit_C 740 includes, for example, a semiconductormemory, an HDD, an SSD, or the like. The storage unit_C 740 storesidentification information, control information, a flag, a parameter,and the like included in a control message which is transmitted and/orreceived in the communication procedure described below. Examples of thecontext 642 stored in the storage unit_C 740 may include a contextstored for each UE, a context stored for each PDU session, and a contextstored for each bearer. The context stored for each UE may include anIMSI, an MSISDN, MM State, a GUTI, a ME Identity, a UE radio accesscapability, a UE network capability, an MS network capability, an accessrestriction, an MME F-TEID, an SGW F-TEID, an eNB address, an MME UE S1AP ID, an eNB UE S1 AP ID, an NR node address, an NR node ID, a WAGaddress, and a WAG ID. Furthermore, the context stored for each PDUsession may include an APN in Use, an assigned session type, IPaddress(es), a PGW F-TEID, an SCEF ID, and a default bearer.

Furthermore, the context stored for each bearer may include an EPSbearer ID, a TI, a TFT, an SGW F-TEID, a PGW F-TEID, an MME F-TEID, aneNB address, an NR node address, a WAG address, an eNB ID, an NR nodeID, and a WAG ID.

1.2.4. Configuration of SMF

Next, FIG. 8 illustrates an example of an apparatus configuration of theSMF_A 230. As illustrated in FIG. 8, the SMF_A 230 includes acontroller_D 800, a network connection unit_D 820, and a storage unit_D840. The network connection unit_D 820 and the storage unit_D 840 areconnected to the controller_D 800 via a bus. In addition, the storageunit_D 840 stores a context 742.

The controller_D 800 of the SMF_A 230 is a function unit for controllingthe entire SMF_A 230 and implements various processes of the entireSMF_A 230 by reading out and performing various types of information andprograms stored in the storage unit_D 840.

The network connection unit_D 820 in the SMF_A 230 is a function unitfor the SMF_A 230 to connect to the AMF_A 240, the UPF_A 235, the UDM,and the PCF. In other words, the SMF_A 230 can transmit and/or receiveuser data and/or control information to and/or from the AMF_A 240, theUPF_A 235, the UDM, and the PCF via the network connection unit_D 820.

Furthermore, the storage unit_D 840 in the SMF_A 230 is a function unitfor storing programs, data, and the like necessary for each operation ofthe SMF_A 230. The storage unit_D 840 of the SMF_A 230 includes, forexample, a semiconductor memory, an HDD, an SSD, or the like. Thestorage unit_D 840 of the SMF_A 230 stores identification information,control information, a flag, a parameter, and the like included in acontrol message which is transmitted and/or received in thecommunication procedure described below. In addition, examples of thecontext 742 stored in the storage unit_D 840 in the SMF_A 230 mayinclude a context stored for each UE, a context stored for each APN, acontext stored for each PDU session, and a context stored for eachbearer. The context stored for each UE may include an IMSI, an MEIdentity, an MSISDN, and a RAT type. The context stored for each APN mayinclude an APN in use. Note that the context stored for each APN may bestored for each data network identifier. The context stored for each PDUsession may include Assigned Session Type, IP Address(es), SGW F-TEID,PGW F-TEID, and Default Bearer. The context stored for each bearer mayinclude an EPS bearer ID, a TFT, an SGW F-TEID, and a PGW F-TEID.

1.2.5. Configuration of PGW/UPF

Next, FIG. 8 illustrates an example of an apparatus configuration of thePGW_A 30 or the UPF_A 235. As illustrated in FIG. 8, each of the PGW_A30 or the UPF_A 235 includes a controller_D 800, a network connectionunit_D 820, and a storage unit_D 840. The network connection unit_D 820and the storage unit_D 840 are connected to the controller_D 800 via abus. In addition, the storage unit_D 840 stores a context 742.

The controller_D 800 in the PGW_A 30 or the UPF_A 235 is a function unitfor controlling the entire PGW_A 30 or UPF_A 235, and implements variousprocesses of the entire PGW_A 30 or UPF_A 235 by reading out andperforming various types of information and programs stored in thestorage unit_D 840.

The network connection unit_D 820 in the PGW_A 30 or the UPF_A 235 is afunction unit for the PGW_A 30 or the UPF_A 235 to connect to the DN(that is, the DN_A 5), the SMF_A 230, another UPF_A 235, and the accessnetwork (that is, the UTRAN_A 20, the E-UTRAN_A 80, and the NG-RAN_A120). In other words, the UPF_A 235 can transmit and/or receive userdata and/or control information to and/or from the DN (that is, the DN_A5), the SMF_A 230, another UPF_A 235, and the access network (that is,the UTRAN_A 20, the E-UTRAN_A 80, and the NG-RAN_A 120) via the networkconnection unit_D 820.

The storage unit_D 840 in the UPF_A 235 is a function unit for storingprograms, data, and the like necessary for each operation of the UPF_A235. The storage unit_D 840 in the UPF_A 235 includes, for example, asemiconductor memory, an HDD, an SSD, or the like. The storage unit_D840 in the UPF_A 235 stores identification information, controlinformation, a flag, a parameter, and the like included in the controlmessage transmitted and/or received in a communication proceduredescribed later. In addition, examples of the context 742 stored in thestorage unit_D 840 in the UPF_A 235 may include a context stored foreach UE, a context stored for each APN, a context stored for each PDUsession, and a context stored for each bearer. The context stored foreach UE may include an IMSI, an ME Identity, an MSISDN, and a RAT type.The context stored for each APN may include an APN in use. Note that thecontext stored for each APN may be stored for each data networkidentifier. The context stored for each PDU session may include AssignedSession Type, IP Address(es), SGW F-TEID, PGW F-TEID, and DefaultBearer. The context stored for each bearer may include an EPS bearer ID,a TFT, an SGW F-TEID, and a PGW F-TEID.

1.2.6. Information Stored in Storage Unit of Each Apparatus

Next, each piece of information stored in the storage unit of each ofthe above-described apparatuses will be described.

An International Mobile Subscriber Identity (IMSI) is permanentidentification information of a subscriber (user), and is identificationinformation assigned to a user using the UE. The IMSI stored by the UE_A10, the MME_A 40/CPF_A 140/AMF_A 2400, and the SGW_A 35 may be the sameas the IMSI stored by an HSS_A 50.

The EMM State/MM State indicates a mobility management state of the UE_A10 or the MME_A 40/CPF_A 140/AMF_A 240. For example, the EMM State/MMState may be an EMM-REGISTERED state (registered state) in which theUE_A 10 is registered in the network, and/or an EMM-DEREGISTERED state(deregistered state) in which the UE_A 10 is not registered in thenetwork. The EMM State/MM State may be an ECM-CONNECTED state in which aconnection is maintained between the UE_A 10 and the core network,and/or an ECM-IDLE state in which the connection is released. Note thatthe EMM State/MM State may be information for distinguishing a state inwhich the UE_A 10 is registered in the EPC from a state in which theUE_A 10 is registered in the NGC or 5GC.

The Globally Unique Temporary Identity (GUTI) is temporaryidentification information of the UE_A 10. The GUTI includesidentification information (Globally Unique MME Identifier (GUMMEI)) ofthe MME_A 40/CPF_A 140/AMF_A 240 and identification information(M-Temporary Mobile Subscriber Identity (M-TMSI)) of the UE_A 10 in aparticular MME_A 40/CPF_A 140/AMF_A 240. The ME Identity is an ID of theUE_A 10 or the ME, and may be International Mobile Equipment Identity(IMEI) or IMEI Software Version (IMEISV), for example. The MSISDNrepresents a basic phone number of the UE_A 10. The MSISDN stored by theMME_A 40/CPF_A 140/AMF_A 240 may be information indicated by the storageunit of the HSS_A 50. Note that the GUTI may include information foridentifying the CPF_140.

The MME F-TEID is information for identifying the MME_A 40/CPF_A140/AMF_A 240. The MME F-TEID may include an IP address of the MME_A40/CPF_A 140/AMF_A 240, a Tunnel Endpoint Identifier (TEID) of the MME_A40/CPF_A 140/AMF_A 240, or both of them. Furthermore, the IP address ofthe MME_A 40/CPF_A 140/AMF_A 240 and the TEID of the MME_A 40/CPF_A140/AMF_A 240 may be stored independently of each other. The MME F-TEIDmay be identification information for user data, or identificationinformation for control information.

The SGW F-TEID is information for identifying the SGW_A 35. The SGWF-TEID may include an IP address of the SGW_A 35, a TEID of the SGW_A35, or both of them. The IP address of the SGW_A 35 and the TEID of theSGW_A 35 may be stored independently of each other. The SGW F-TEID maybe identification information for user data, or identificationinformation for control information.

The PGW F-TEID is information for identifying the PGW_A 30/UPGW_A130/SMF_A 230/UPF_A 235. The PGW F-TEID may include an IP address of thePGW_A 30/UPGW_A 130/SMF_A 230/UPF_A 235, a TEID of the PGW_A 30/UPGW_A130/SMF_A 230/UPF_A 235, or both of them. In addition, the IP address ofthe PGW_A 30/UPGW_A 130/SMF_A 230/UPF_A 235 and the TEID of the PGW_A30/UPGW_A 130/SMF_A 230/UPF_A 235 may be stored independently of eachother. The PGW F-TEID may be identification information for user data,or identification information for control information.

The eNB F-TEID is information for identifying the eNB_A 45. The eNBF-TEID may include an IP address of the eNB_A 45, a TEID of the eNB_A45, or both of them. The IP address of the eNB_A 45 and the TEID of theSGW_A 35 may be stored independently of each other. The eNB F-TEID maybe identification information for user data, or identificationinformation for control information.

The APN may be identification information for identifying the corenetwork and an external network such as the DN. Furthermore, the APN canalso be used as information for selecting a gateway such as the PGW_A30/UPGW_A 130/UPF_A 235 for connecting the core network A_90. Note thatthe APN may be a Data Network Name (DNN). Therefore, the APN may berepresented by a DNN, or the DNN may be represented by the APN.

Note that the APN may be identification information for identifying sucha gateway, or identification information for identifying an externalnetwork such as the DN. Note that, in a case that multiple gatewaysconnecting the core network and the DN are deployed, there may bemultiple gateways that can be selected according to the APN.Furthermore, one gateway may be selected among such multiple gateways byanother method using identification information other than the APN.

The UE Radio Access Capability is identification information indicatinga radio access capability of the UE_A 10. The UE Network Capabilityincludes an algorithm of security supported by the UE_A 10 and a keyderivation function. The MS Network Capability is information including,in the UE_A 10 having a function of a GERAN_A 25 and/or a UTRAN_A 20,one or more pieces of information necessary for an SGSN_A 42. The AccessRestriction is registration information for access restriction. The eNBAddress is an IP address of the eNB_A 45. The MME UE S1AP ID isinformation for identifying the UE_A 10 in the MME_A 40/CPF_A 140/AMF_A240. The eNB UE S1AP ID is information for identifying the UE_A 10 inthe eNB_A 45.

The APN in Use is an APN recently used. The APN in Use may be DataNetwork Identifier. This APN may include identification information ofthe network and identification information of a default operator.Furthermore, the APN in Use may be information for identifying a DN withwhich the PDU session is established.

The Assigned Session Type is information indicating a PDU session type.The Assigned Session Type may be Assigned PDN Type. The PDU session typemay be IP, or non-IP.

Furthermore, in a case that the PDU session type is IP, informationindicating a PDN type assigned by the network may be further included.Note that the Assigned Session Type may be IPv4, IPv6, or IPv4v6.

Unless otherwise specifically described, the IP Address refers to the IPaddress assigned to the UE. The IP address may be an IPv4 address, anIPv6 address, an IPv6 prefix, or an interface ID. Note that in a casethat the Assigned Session Type indicates non-IP, an element of the IPAddress may not be included.

The DNN is identification information for identifying the core network_B190 and an external network such as the DN. Furthermore, the DNN canalso be used as information for selecting a gateway such as the UPGW_A130 or the PF_A 235 connecting the core network_B 190.

Note that the DNN may be identification information for identifying sucha gateway, or identification information for identifying an externalnetwork such as the DN. Note that, in a case that multiple gatewaysconnecting the core network_B 190 and the DN are deployed, there may bemultiple gateways that can be selected according to the DNN.Furthermore, one gateway may be selected among such multiple gateways byanother method using identification information other than the DNN.

Furthermore, the DNN may be information equivalent to the APN, ordifferent from the APN. Note that in a case that the DNN is theinformation different from the APN, each apparatus may manageinformation indicating correspondence between the DNN and the APN,perform a procedure to inquire the APN by using the DNN, or perform aprocedure to inquire the DNN by using the APN.

SCEF ID is an IP address of an SCEF_A 46 used in the PDU session. TheDefault Bearer is information acquired and/or created in a case that aPDU session is established and is EPS bearer identification informationfor identifying a default bearer associated with the PDU session.

The EPS Bearer ID is identification information of the EPS bearer. TheEPS Bearer ID may be identification information for identifyingSignalling Radio Bearer (SRB) and/or Control-plane Radio bearer (CRB),or identification information for identifying Data Radio Bearer (DRB).The Transaction Identifier (TI) is identification information foridentifying a bidirectional message flow (Transaction). Note that theEPS Bearer ID may be EPS bearer identification information foridentifying a dedicated bearer. Therefore, the EPS bearer ID may beidentification information for identifying the EPS bearer different fromthe default bearer. The TFT indicates all packet filters associated withthe EPS bearer. The TFT is information for identifying some pieces ofuser data to be transmitted and/or received, and thus, the UE_A 10 usesthe EPS bearer associated with the TFT to transmit and/or receive theuser data identified by the TFT. In still other words, the UE_A 10 usesa Radio Bearer (RB) associated with the TFT to transmit and/or receivethe user data identified by the TFT. The TFT may associate the user datasuch as application data to be transmitted and/or received with anappropriate transfer path, and may be identification information foridentifying the application data. The UE_A 10 may use the default bearerto transmit and/or receive the user data which cannot be identified bythe TFT. The UE_A 10 may store in advance the TFT associated with thedefault bearer.

The Default Bearer is EPS bearer identification information foridentifying a default bearer associated with a PDU session. Note thatthe EPS bearer may be a logical communication path established betweenthe UE_A 10 and the PGW_A 30/UPGW_A 130/UPF_A 235, or a communicationpath constituting the PDN connection/PDU session. Furthermore, the EPSbearer may be a default bearer, or a dedicated bearer. Furthermore, theEPS bearer may include an RB established between the UE_A 10 and thebase station and/or the access point in the access network. Furthermore,the RB and the EPS bearer may be associated with each other on aone-to-one basis. Therefore, identification information of the RB may beassociated with the identification information of the EPS bearer on aone-to-one basis, or may be the same identification information as theidentification information of the EPS bearer. Note that the RB may be anSRB and/or a CRB, or a DRB. Furthermore, the Default Bearer may beinformation that the UE_A 10 and/or the SGW_A 35 and/or the PGW_A30/UPGW_A 130/SMF_A 230/UPF_A 235 acquire from the core network in acase that the PDU session is established. Note that the default beareris an EPS bearer first established during the PDN connection/PDUsession, and is such an EPS bearer that only one bearer can beestablished during one PDN connection/PDU session. The default bearermay be an EPS bearer that can be used for communication of user data notassociated with the TFT. The dedicated bearer is an EPS bearerestablished after the default bearer is established during the PDNconnection/PDU session, and is such an EPS bearer that multiple bearerscan be established during one PDN connection/PDU session. The dedicatedbearer is an EPS bearer that can be used for communication of user datanot associated with the TFT.

User Identity is information for identifying a subscriber. The UserIdentity may be an IMSI, or an MSISDN. Furthermore, the User Identitymay also be identification information other than the IMSI or theMSISDN. Serving Node Information is information for identifying theMME_A 40/CPF_A 140/AMF_A 240 used in a PDU session, and may be an IPaddress of the MME_A 40/CPF_A 140/AMF_A 240.

The eNB Address is an IP address of the eNB_A 45. The eNB ID isinformation for identifying the UE in the eNB_A 45. MME Address is an IPaddress of the MME_A 40/CPF_A 140/AMF_A 240. MME ID is information foridentifying the MME_A 40/CPF_A 140/AMF_A 240. The NR node Address is anIP address of the NR node_A 122. The NR node ID is information foridentifying the NR node_A 122. The WAG Address is an IP address of theWAG. The WAG ID is information for identifying the WAG.

The anchor or anchor point is a UFP having a gateway function of the DNand the PDU session. The UPF to be the anchor point may be a PDU sessionanchor or an anchor.

The SSC mode indicates a mode of Session and Service Continuitysupported by a system and/or each apparatus in the 5GC. To be morespecific, the SSC mode may be a mode indicating a type of the sessionand service continuity supported by a PDU session established betweenthe UE_A 10 and the anchor point). Here, the anchor point may be theUPGW or may be the UPF_A 235. Note that the SSC mode may be a modeindicating a type of the session and service continuity configured foreach PDU session. The SSC mode may be configured to include three modesof SSC mode 1, SSC mode 2, and SSC mode 3. The SSC mode is associatedwith the anchor point and cannot be changed while the PDU session isbeing established.

Furthermore, the SSC mode 1 in the present embodiment is a mode of thesession and service continuity in which the same UPF is continuouslymaintained as the anchor point regardless of the access technology suchas the Radio Access Technology (RAT) and the cell the UE_A 10 uses toconnect to a network. To be more specific, the SSC mode 1 may be a modein which even in a case that the mobility of the UE_A 10 occurs, thesession and service continuity is achieved without changing the anchorpoint used by the established PDU session.

Furthermore, the SSC mode 2 in the present embodiment is a mode of thesession and service continuity in which in a case that an anchor pointassociated with one SSC mode 2 is included in a PDU session, the PDUsession is previously released, and subsequently a PDU session isestablished. To be more specific, the SSC mode 2 is a mode in which in acase that a relocation of the anchor point occurs, the PDU session isdeleted once, and then, a new PDU session is established.

Furthermore, the SSC mode 2 is a mode of the session and servicecontinuity in which the same UPF is continuously maintained as theanchor point only in a serving area of the UPF. To be more specific, theSSC mode 2 may be a mode in which as long as the UE_A 10 is in theserving area of the UPF, the session and service continuity is achievedwithout changing the UPF used by the established PDU session.Furthermore, the SSC mode 2 may be a mode in which in a case that themobility the UE_A 10 leaves the serving area of the UPF occurs, thesession and service continuity is achieved by changing the UPF used bythe established PDU session.

Here, the serving area of the TUPF may be an area in which one UPF canprovide a session and service continuity function, or a subset of theaccess network such as the RAT or the cell used in a case that the UE_A10 connects to a network. Furthermore, the subset of the access networkmay be a network including one or multiple RATs and/or cells, or may bethe TA.

Furthermore, the SSC mode 3 in the present embodiment is a mode of thesession and service continuity in which without releasing the PDUsession between the UE and the anchor point, a PDU session can beestablished between a new anchor point and the UE for the same DN.

Furthermore, the SSC mode 3 is a mode of the session and servicecontinuity that allows, before disconnecting the PDU session and/or thecommunication path established between the UE_A 10 and the UPF, a newPDU session and/or communication path to be established via a new UPFfor the same DN. Furthermore, the SSC mode 3 may be a mode of thesession and service continuity that allows the UE_A 10 to bemulti-homed.

And/or, the SSC mode 3 may be a mode that allows the session and servicecontinuity using multiple PDU sessions and/or the UPFs associated withthe PDU sessions. In other words, in the case of the SSC mode 3, eachapparatus may achieve the session and service continuity using themultiple PDU sessions, or may achieve the session and service continuityusing the multiple TUPFs.

Here, in the case that each apparatus establishes a new PDU sessionand/or communication path, a new UPF may be selected by the network, ora new UPF may be an optimal UPF for a location at which the UE_A 10connects to the network. Furthermore, in a case that the multiple PDUsessions and/or the UPFs used by the PDU sessions are effective, theUE_A 10 may correlate the application and/or flow communications to anew established PDU session, immediately or based on the completion ofthe communications.

1.3. Description of Initial Procedure

Next, before describing detailed processes of an initial procedure inthe present embodiment, in order to avoid redundant descriptions,terminology specific to the present embodiment and primaryidentification information used in each procedure will be describedbeforehand.

The network in the present embodiment refers to at least some of theaccess network_A 20/80, the access network_B 80/120, the core network_A90, the core network_B 190, the DN_A 5, and the PDN_A 6. One or moreapparatuses included in at least some of the access network_A 20/80, theaccess network_B 80/120, the core network_A 90, the core network_B 190,the DN_A 5, and the PDN_A 6 may also be referred to as a network or anetwork apparatus. Specifically, the expression “the network performstransmission and/or reception of a message and/or performs a procedure”signifies that “an apparatus (network apparatus) in the network performstransmission and/or reception of a message and/or performs a procedure”.

A Session Management (SM) message (also referred to as aNon-Access-Stratum (NAS) SM message or an SM message) in the presentembodiment may be a NAS message used in a procedure for the SM (alsoreferred to as a session management procedure or an SM procedure), ormay be a control message transmitted and/or received between the UE_A 10and the SMF_A 230 via the AMF_A 240. Furthermore, the SM message mayinclude a PDU session establishment request message, a PDU sessionestablishment accept message, a PDU session completion message, a PDUsession reject message, a PDU session modification request message, aPDU session modification accept message, a PDU session modificationreject message, and the like. The procedure for SM may include a PDUsession establishment procedure, a PDU session modification procedure,and the like.

Note that, among the SM messages, a message transmitted by the UE_A 10is represented as an SM request message. Specifically, the PDU sessionestablishment request message and the PDU session modification requestmessage are SM request messages.

Furthermore, a Tracking Area (TA) in the present embodiment is a rangethat can be represented by location information of the UE_A 10 managedby the core network, and may include one or more cells, for example.Furthermore, the TA may be a range in which a control message such as apaging message is broadcast, or a range in which the UE_A 10 can movewithout performing a handover procedure.

A TA list in the present embodiment is a list including one or more TAsallocated to the UE_A 10 by the network. Note that, while the UE_A 10 ismoving within the one or more TAs included in the TA list, the UE_A 10can move without performing the registration procedure. In other words,the TA list may be an information group indicating an area in which theUE_A 10 can move without performing the registration procedure.

A Network Slice in the present embodiment is a logical network thatprovides particular network capabilities and network performance.Hereinafter, the network slice is also referred to as a NW slice.

The Network Slice Instance (NSI) in the present embodiment is an entityof each of one or multiple Network Slices configured in the corenetwork_B 190. The NSI in the present embodiment may include a virtualNetwork Function (NF) generated using a Network Slice Template (NST).Here, the NST is associated with a resource request for providing arequired communication service or capability, and is a logicalexpression of one or multiple Network Functions (NFs). Specifically, theNSI may be an aggregation including multiple NFs in the core network_B190. The NSI may be a logical network configured to classify the userdata delivered through a service or the like. The network slice mayinclude at least one or more NFs. The NF included in the network slicemay be an apparatus shared by another network slice or otherwise. TheUE_A 10 and/or the apparatuses in the network can be assigned to one ormultiple network slices, based on NSSAI and/or S-NSSAI and/or UE usagetype and/or one or multiple network slice type IDs and/or registrationinformation such as one or multiple NS IDs and/or the APN.

The S-NSSAI in the present embodiment is an abbreviation for SingleNetwork Slice Selection Assistance information, and is information foridentifying the network slice. The S-NSSAI may include a Slice/Servicetype (SST) and a Slice Differentiator (SD). The S-NSSAI may include onlythe SST, or may include both the SST and the SD. Here, the SST isinformation indicating an operation of the network slice expected interms of the function and the service. Also, the SD may be informationthat complements the SST in a case of selecting one NSI from themultiple NSIs indicated by the SST. The S-NSSAI may be informationunique to each Public Land Mobile Network (PLMN), may be standardinformation common to the PLMNs, or may be information specific to anetwork operator different for each PLMN.

To be more specific, the SST and/or the SD may be standard information(Standard Value) common to the PLMNs, or may be information (NonStandard Value) specific to a network operator different for each PLMN.

The network may store one or multiple pieces of S-NSSAI for theregistration information of the UE_A 10 as the default S-NSSAI.

The single Network Slice Selection Assistance information (NSSAI) in thepresent embodiment is a group of pieces of S-NSSAI. Each piece ofS-NSSAI included in the NSSAI is information that assists the accessnetwork or the core network to select the NSI. The UE_A 10 may store theNSSAI allowed by the network for each PLMN. Furthermore, the NSSAI maybe information used to select the AMF_A 240.

An operator A's network in the present embodiment is a network operatedby a network operator A (operator A). Here, for example, the operator Amay deploy a NW slice common to an operator B described below.

An operator B's network in the present embodiment is a network operatedby a network operator B (operator B). Here, for example, the operator Bmay deploy a NW slice common to the operator A.

A first NW slice in the present embodiment is a NW slice to which theestablished PDU session belongs in a case that the UE connects to aparticular DN. Note that, for example, the first NW slice may be a NWslice managed in the operator A's network, or may be a NW slice commonlymanaged in the operator B's network.

A second NW slice in the present embodiment is a NW slice to which a PDUsession belongs, the PDU session capable of connecting to the DN towhich a PDU session belonging to the first NW slice connects. Note thatthe first NW slice and the second NW slice may be operated by the sameoperator, or may be operated by different operators.

An equivalent PLMN in the present embodiment is a PLMN treated to be thePLMN the same as any PLMN in the network.

The Dedicated Core Network (DCN) in the present embodiment is one ormultiple particular subscriber type dedicated core networks configuredin the core network_A 90. Specifically, a DCN for a UE registered as auser of Machine to Machine (M2M) communication function may beconfigured in the core network_A 90, for example. In addition, a defaultDCN for a UE with no proper DCN may be configured in the core network_A90. Furthermore, in the DCN, at least one or more MMEs_A 40 or SGSNs_A42 may be located, and further, at least one or more SGWs_A 35, PGWs_A30, or PCRFs_A 60 may be located. Note that the DCN may be identified bya DCN ID, and further, the UE may be assigned to one DCN, based on theinformation such as the UE usage type and/or the DCN ID.

A first timer in the present embodiment is a timer managing aninitiation of a procedure for session management such as a PDU sessionestablishment procedure and/or a transmission of a Session Management(SM) message such as a PDU session establishment request message, andmay be information indicating a value of a back-off timer for managing asession management behavior. Hereinafter, the first timer and/or theback-off timer may be referred to as a timer. While the first timer isrunning, the initiation of the procedure for session management and/orthe transmission and/or reception of the SM message by each apparatusmay be prohibited. Note that the first timer may be configured to beassociated with at least one of a congestion control unit applied by theNW and/or a congestion control unit identified by the UE. For example,the first timer may be configured in at least one unit of an APN/DNNunit and/or an identification information unit indicating one ormultiple NW slices and/or a rejection cause value unit in the sessionmanagement procedure and/or a session unit in which the rejection isindicated in the session management procedure and/or a PTI unit in thesession management procedure.

Note that the SM message may be a NAS message used in the procedure forsession management, or may be a control message transmitted and/orreceived between the UE_A 10 and the SMF_A 230 via the AMF_A 240.Furthermore, the SM message may include a PDU session establishmentrequest message, a PDU session establishment accept message, a PDUsession completion message, a PDU session reject message, a PDU sessionmodification request message, a PDU session modification accept message,a PDU session modification reject message, and the like. Furthermore,the procedure for session management may include a PDU sessionestablishment procedure, a PDU session modification procedure, and thelike. In these procedures, a back-off timer value may be included foreach message received by the UE_A 10. The UE may configure, as the firsttimer, the back-off timer received from the NW, a timer value in anothermanner, or a random value. In a case of receiving multiple back-offtimers from the NW, the UE may manage multiple “first timers”corresponding to the multiple back-off timers, or may select one timervalue from the multiple back-off timer values received from the NW,based on the policy that the UE holds to configure and manage theselected timer as the first timer. For example, in a case of receivingtwo back-off timer values, the UE configures and manages the back-offtimer values received from the NW as the “first timer #1” and the “firsttimer #2”. The UE may select one value from the multiple back-off timervalues received from the NW, based on the policy that the UE holds toconfigure and manage the selected timer as the first timer.

The UE_A 10, in a case of receiving multiple back-off timer values fromthe NW, may manage multiple “first timers” corresponding to the multipleback-off timers. Here, in the following, the multiple “first timers”received by the UE_A 10 may be described, for example, as the “firsttimer #1” or the “first timer #2” in order to be distinguished from eachother. Note that the multiple back-off timers may be acquired in asingle session management procedure, or may be acquired in differentsession management procedures.

Here, as described above, the first timer may be a back-off timer thatis configured for, based on the information for identifying one NWslice, the multiple associated NW slices to prohibit reconnection, ormay be a back-off timer that is configured in units of a combination ofthe APN/DNN and one NW slice to prohibit reconnection, withoutlimitation, and may be a back-off timer that is configured in units of acombination of the APN/DNN and the multiple associated NW slices, basedon the information for identifying one NW slice to prohibitreconnection.

Re-attempt information included in eleventh identification informationin the present embodiment is information indicated to the UE_A 10 by thenetwork (NW) regarding whether to allow reconnection using the same DNNinformation and/or S-NSSAI information for the rejected PDU sessionestablishment request (S1100).

At this time, in the PDU session establishment request (1100), in a casethat the UE has made a PDU session establishment request not including aDNN (S1100), not including the DNN is referred to as identicalinformation. In the PDU session establishment request (1100), in a casethat the UE has made a PDU session establishment request not includingS-NSSAI (S1100), the S-NSSAI being not included is referred to asidentical information.

Note that the re-attempt information may be configured in units of UTRANaccess and/or E-UTRAN access and/or NR access and/or slice informationand/or equivalent PLMN and/or S1 mode and/or NW mode.

Further, the re-attempt information specified in units of access (UTRANaccess, E-UTRAN access, NR access) may be information indicating areconnection using the identical information to the network on theassumption of the access change. The re-attempt information specified inunits of slice may be specified with slice information different fromthe rejected slice, and a reconnection using the specified sliceinformation may be allowed.

Furthermore, the re-attempt information specified in units of equivalentPLMN may be information indicating that in a case that the PLMN ischanged, in a case that the PLMN after the change is an equivalent PLMN,a reconnection using the identical information is allowed. In a casethat the PLMN after the change is not an equivalent PLMN, the re-attemptinformation may be information indicating that the reconnection usingthis procedure is not allowed.

Furthermore, the re-attempt information specified in units of mode (S1mode, N1 mode) may be information indicating that, in a case that themode is changed, in a case that the mode after the change is an S1 mode,a reconnection using the identical information allowed. In a case thatthe mode after the change is an S1 mode, the re-attempt information maybe information indicating that a reconnection using the identicalinformation is not allowed.

A network slice association rule in the present embodiment is a rule forassociating information identifying multiple network slices. Note thatthe network slice association rule may be received in the PDU sessionreject message, or may be preconfigured for the UE_A 10. Furthermore,the newest network slice association rule may be applied to the UE_A 10.Conversely, the UE_A 10 may perform a behavior based on the newestnetwork slice association rule. For example, in a case that the UE_A 10receives a new network slice association rule in the PDU session rejectmessage while the network slice association rule is configured for theUE_A 10 in advance, the UE_A 10 may update the network slice associationrule held in the UE_A 10.

A back-off timer priority management rule in the present embodiment is arule configured for the UE_A 10 to collectively manage multiple back-offtimers occurring in multiple PDU sessions on a single back-off timer.For example, in a case that in a case that conflicting or overlappingcongestion controls are applied and in a case that the UE holds multipleback-off timers, the UE_A 10 may collectively manage multiple back-offtimers, based on the back-off timer priority management rule. Note thata pattern in which the conflicting or overlapping congestion controlsoccur is a case that a congestion control based on only the DNN and acongestion control based on both the DNN and the slice information areapplied at the same time, and in this case, the congestion control basedon only the DNN is prioritized. Note that the back-off timer prioritymanagement rule may not be limited to this. Note that the back-off timermay be a first timer included in the PDU session reject message.

A first state in the present embodiment is a state in which eachapparatus has completed the registration procedure and the PDU sessionestablishment procedure, and one or more of the first to fourthcongestion controls are applied to the UE_A 10 and/or each apparatus.Here, the UE_A 10 and/or each apparatus may be, as a result of thecompletion of the registration procedure, in a state that the UE_A 10 isregistered with the network (RM-REGISTERED state), and the completion ofthe PDU session establishment procedure may be a state in which the UE_A10 receives the PDU session establishment reject message from thenetwork.

The congestion control in the present embodiment includes one ormultiple congestion controls of a first congestion control to a fourthcongestion control. Note that the control of the UE by the NW isachieved by the congestion control recognized by the first timer and theUE, and the UE may store associations of these pieces of information.

The first congestion control in the present embodiment indicates acongestion control for control signal associated with parameters of theDNN. For example, in a case that a congestion to a DNN #A is detected inthe NW, and in a case that the NW recognizes that a UE-initiated sessionmanagement request associated with parameters only of the DNN #A ismade, the NW may apply the first congestion control. Note that even in acase that the UE-initiated session management request does not includethe DNN information, the NW may select a default DNN as a congestioncontrol target on the initiative of the NW. Alternatively, the NW mayapply the first congestion control even in a case that the NW recognizesthat the UE-initiated session management request including the DNN #Aand S-NSSAI #A is made. In a case that the first congestion control isapplied, the UE may prohibit the UE-initiated session management requestassociated with only the DNN #A.

In other words, the first congestion control in the present embodimentmay be a congestion control for control signal associated with the DNN,and a congestion control due to connectivity to the DNN being in acongested state. For example, the first congestion control may be acongestion control to regulate connection to the DNN #A in allconnectivities. Here, the connection to the DNN #A in the allconnectivities may be a connection of the DNN #A in a connectivity usingany S-NSSAI available to the UE, or may be a connection of the DNN #Athrough a network slice to which the UE is connectable. Furthermore, aconnectivity to the DNN #A not through a network slice may be included.

A second congestion control in the present embodiment indicates acongestion control for control signal associated with parameters of theS-NSSAI. For example, in a case that a control signal congestion to theS-NSSAI #A is detected in the NW, and in a case that the NW recognizesthat a UE-initiated session management request associated withparameters only of the S-NSSAI #A is made, the NW may apply the secondcongestion control. In a case that the second congestion control isapplied, the UE may prohibit the UE-initiated session management requestassociated with only the S-NSSAI #A.

In other words, the second congestion control in the present embodimentmay be a congestion control for control signal associated with theS-NSSAI, and a congestion control due to the network slice selected bythe S-NSSAI being in a congested state. For example, the secondcongestion control may be a congestion control to regulate allconnections, based on the S-NSSAI #A. Specifically, the secondcongestion control may be a congestion control to regulate connectionsto the all DNNs through a network slice selected by the S-NSSAI #A.

A third congestion control in the present embodiment indicates acongestion control for control signal associated with parameters of theDNN and the S-NSSAI. For example, in a case that a control signalcongestion to the DNN #A and a control signal congestion to the S-NSSAI#A are simultaneously detected in the NW, and in a case that the NWrecognizes that a UE-initiated session management request associatedwith parameters of the DNN #A and the S-NSSAI #A is made, the NW mayapply the third congestion control. Note that even in a case that theUE-initiated session management request does not include informationindicating the DNN, the NW may select a default DNN collectively as acongestion control target on the initiative of the NW. In a case thatthe third congestion control is applied, the UE may prohibit theUE-initiated session management request associated with the parametersof the DNN #A and the S-NSSAI #A.

In other words, the third congestion control in the present embodimentmay be a congestion control for control signal associated with theparameters of the DNN and the S-NSSAI, and a congestion control due toconnectivity to the DNN through the network slice selected based on theS-NSSAI being in a congested state. For example, the third congestioncontrol may be congestion control to regulate connection to the DNN #Ain the connectivities based on the S-NSSAI #A.

A fourth congestion control in the present embodiment indicates acongestion control for control signal associated with parameters of atleast one of the DNN and/or the S-NSSAI. For example, in a case that acontrol signal congestion to the DNN #A and a control signal congestionto the S-NSSAI #A are simultaneously detected in the NW, and in a casethat the NW recognizes that a UE-initiated session management requestassociated with parameters of at least one of the DNN #A and/or theS-NSSAI #A is made, the NW may apply the fourth congestion control. Notethat even in a case that the UE-initiated session management requestdoes not include information indicating the DNN, the NW may select adefault DNN collectively as a congestion control target on theinitiative of the NW. In a case that the fourth congestion control isapplied, the UE may prohibit the UE-initiated session management requestassociated with the parameters of at least one of the DNN #A and/or theS-NSSAI #A.

In other words, the fourth congestion control in the present embodimentmay be a congestion control for control signal associated with theparameters of the DNN and the S-NSSAI, and a congestion control due tothe network slice selected based on the S-NSSAI and connectivity to theDNN being in a congested state. For example, the fourth congestioncontrol may be a congestion control to regulate all connections based onthe S-NSSAI #A and a congestion control to regulate connection to theDNN #A in all connectivities. Specifically, the fourth congestioncontrol may be a congestion control to regulate connections to the allDNNs through a network slice selected by the S-NSSAI #A and a congestioncontrol to regulate connection to the DNN #A in all connectivities.Here, the connection to the DNN #A in the all connectivities may be aconnection of the DNN #A in a connectivity using any S-NSSAI availableto the UE, or may be a connection of the DNN #A through a network sliceto which the UE is connectable. Furthermore, a connectivity to the DNN#A not through a network slice may be included.

Thus, the fourth congestion control using the DNN #A and S-NSSAI #A asthe parameters may be a congestion control simultaneously performing thefirst congestion control using the DNN #A as the parameters and thesecond congestion control using the S-NSSAI #A as the parameters.

A first behavior in the present embodiment is a behavior in which the UEstores slice information transmitted in a first PDU sessionestablishment request message in association with transmitted PDUsession identification information. In the first behavior, the UE maystore the slice information transmitted in the first PDU sessionestablishment request message, or may store the slice informationreceived in a case that the first PDU session establishment request isrejected.

A second behavior in the present embodiment is a behavior in which theUE transmits a PDU session establishment request to connect to theAPN/DNN the same as the first PDU session establishment request by usinganother piece of slice information different from the slice informationspecified in the first PDU session establishment. Specifically, thesecond behavior may be a behavior in which in a case that a back-offtimer value received from the network is zero or invalid, the UEtransmits a PDU session establishment request to connect to the APN/DNNthe same as the first PDU session establishment request by using anotherpiece of slice information different from the slice informationspecified in the first PDU session establishment. Additionally, thesecond behavior may be a behavior in which in a case that the first PDUsession is rejected because radio access of the particular PLMN to whichthe specified APN/DNN connects is not supported, or in a case that thefirst PDU session is rejected for temporary causes, the UE transmits aPDU session establishment request to connect to the APN/DNN the same asthe APN/DNN included in the first PDU session establishment request, byusing another piece of slice information different from the sliceinformation specified in the first PDU session establishment.

A third behavior in the present embodiment is a behavior in which in acase that the PDU session establishment request is rejected, the UE doesnot transmit a new PDU session establishment request by use of the sameidentification information until the first timer expires. Specifically,the third behavior may be a behavior in which in a case that a back-offtimer value received from the network is neither zero nor invalid, theUE does not transmit a new PDU session establishment request by use ofthe same identification information until the first timer expires. Here,the same identification information may mean whether firstidentification information and/or second identification information tobe carried on the new PDU session establishment request is the same asthe first identification information and/or the second identificationinformation transmitted in the rejected PDU session establishmentrequest.

The third behavior may be a behavior in which in a case that anotherPLMN is selected, or in a case that another NW slice is selected and arejection cause for a configuration failure for network operation isreceived, in a case that a back-off timer received in a case that thefirst PDU session establishment request is rejected is running, the UEdoes not transmit a new PDU session establishment request by use of thesame identification information until the first timer expires.

To be specific, the PDU session for which a new PDU sessionestablishment request in the third behavior is not transmitted may be aPDU session in which the congestion control associated with the firsttimer is applied. More specifically, the third behavior may be theconnectivity in accordance with the type of the congestion controlassociated with the first timer, and may be a behavior in which a newPDU session establishment request is not transmitted to the PDU sessionwith the DNN and/or S-NSSAI associated with the congestion control. Notethat the process from which the UE is prohibited by the present behaviormay be an initiation of the procedure for session management including aPDU session establishment request and/or transmission and/or receptionof an SM message.

A fourth behavior in the present embodiment is a behavior in which in acase that the PDU session establishment request is rejected, the UE doesnot transmit a new PDU session establishment request not carrying theslice information and the DNN/APN information until the first timerexpires. Specifically, the fourth behavior may be a behavior in which ina case that a back-off timer received by the UE from the network isneither zero nor invalid, the UE does not transmit a new PDU sessionestablishment request not carrying the slice information and the DNN/APNinformation until the first timer expires.

A fifth behavior in the present embodiment is a behavior in which in acase that the PDU session establishment request is rejected, the UE doesnot transmit a new PDU session establishment request by use of the sameidentification information. Specifically, the fifth behavior may be abehavior in which in a case that PDP types supported in the UE and thenetwork are different and in a case that the UE is in the equivalentPLMN, the UE does not transmit a new PDU session establishment requestby use of the same identification information.

A sixth behavior in the present embodiment is a behavior in which in acase that the PDU session establishment request is rejected, the UEtransmits a new PDU session establishment request as an initialprocedure by use of the same identification information. Specifically,the sixth behavior may be a behavior in which in a case that the firstPDU session establishment request is rejected because there is no PDNsession context of interest in a handover from the non-3GPP access, theUE transmits a new PDU session establishment request as the initialprocedure by use of the same identification information.

A seventh behavior in the present embodiment is a behavior in which in acase that the UE selects another NW slice in the procedure for selectinga PLMN, the UE continues a back-off timer received in a case that theprevious PDU session establishment request is rejected. Specifically,the seventh behavior may be a behavior in which in a case that the UEselects a PLMN in a case that the first PDU session establishmentrequest is rejected, and in a case that a NW slice common to the NWslice specified in the first PDU session establishment request can bespecified in the selected PLMN, the UE continues a back-off timerreceived in a case that the first PDU session establishment request isrejected.

An eighth behavior in the present embodiment is a behavior in which theUE configures a value notified from the network or a value preconfiguredfor the UE as a first timer value. Specifically, the eighth behavior maybe a behavior in which the UE configures the back-off timer valuereceived in a reject notification for the first PDU sessionestablishment request as the first timer value, or may be a behavior inwhich the UE configures a value preconfigured for or held in the UE asthe first timer value. Note that the eighth behavior in the case that atimer preconfigured for or held in the UE is configured as the firsttimer value may be limited to a case where the UE is in a HPLMN or theequivalent PLMN.

A ninth behavior in the present embodiment is a behavior in which in acase that the PDU session establishment request message is rejected, theUE does not transmit a new PDU session establishment request until aterminal power is turned on/off, or a Universal Subscriber IdentityModule (USIM) is inserted or removed. Specifically, the ninth behaviormay be a behavior in which in a case that the back-off timer receivedfrom the network is invalid, or in a case that the first PDU sessionrejection causes of the UE and the network are different in the PDP typefrom each other, the UE does not transmit a new PDU sessionestablishment request until a terminal power is turned on/off, or a USIMis inserted or removed. The ninth behavior may be a behavior in which ina case that the first PDU session is rejected because the specifiedAPN/DNN is not supported wirelessly in the connected PLMN, and in a casethat there is no information element of the back-off timer from thenetwork and there is no Re-attempt information, or in a case that a PDUsession reconnection to the equivalent PLMN is allowed, the UE does nottransmit a new PDU session establishment request until a terminal poweris turned on/off, or a USIM is inserted or removed in the connectedPLMN. The ninth behavior may be a behavior in which in a case that thefirst PDU session is rejected because the specified APN/DNN is notsupported wirelessly in the connected PLMN, and in a case that there isno information element of the back-off timer from the network and thereis no Re-attempt information, or in a case that a PDU sessionreconnection to the equivalent PLMN is not allowed, the UE does nottransmit a new PDU session establishment request until a terminal poweris turned on/off, or a USIM is inserted or removed in the connectedPLMN. The ninth behavior may be a behavior in which in a case that thefirst PDU session is rejected because the specified APN/DNN is notsupported wirelessly in the connected PLMN, and in a case that theback-off timer from the network is neither zero nor invalid, the UE doesnot transmit a new PDU session establishment request until a terminalpower is turned on/off, or a USIM is inserted or removed. The ninthbehavior may be a behavior in which in a case that the first PDU sessionis rejected because the specified APN/DNN is not supported wirelessly inthe connected PLMN, and in a case that the back-off timer from thenetwork is invalid, the UE does not transmit a new PDU sessionestablishment request until a terminal power is turned on/off, or a USIMis inserted or removed.

A tenth behavior in the present embodiment is a behavior in which in acase that the PDU session establishment request is rejected, the UEtransmits a new PDU session establishment request. Specifically, thetenth behavior may be a behavior in which in a case that the back-offtimer received from the network is zero, or in a case that the first PDUsession establishment request is rejected for temporary causes, andfurther in a case that there is no back-off timer information elementitself notified from the network, the UE transmits a new PDU sessionestablishment request. The tenth behavior may be a behavior in which ina case that another PLMN is selected or another NW slice is selected, ina case that the first PDU session establishment request is rejected fortemporary causes, and in a case that the back-off timer is not runningfor the APN/DNN of interest in the selected PLMN or the back-off timerreceived from the network is invalid, the UE transmits a new PDU sessionestablishment request. The tenth behavior may be a behavior in which ina case that the first PDU session establishment request is rejectedbecause the PDP types of the UE and the network are different from eachother, and in a case that the Re-attempt information is not received ina case that a different PLMN is selected, or a PLMN not in an equivalentPLMN list is selected, or in a case that the PDP type is changed, or ina case that a terminal power is turned on/off, or a USIM is inserted orremoved, the UE transmits a new PDU session establishment request. Thetenth behavior may be a behavior in which in a case that the first PDUsession is rejected because the specified APN/DNN is not supportedwirelessly in the connected PLMN, and in a case that the back-off timernotified from the network is zero, the UE transmits a new PDU sessionestablishment request.

An eleventh behavior in present embodiment is a behavior in which the UEignores the first timer and the Re-attempt information. Specifically,the eleventh behavior may be a behavior in which in a case that thefirst PDU session establishment request is rejected because there is noPDN session context of interest in a handover from the non-3GPP access,or in a case that the first PDU session establishment is rejectedbecause the number of bearers provided in the PDN connection reaches themaximum allowed number, the UE ignores the first timer and theRe-attempt information.

A twelfth behavior in the present embodiment is a behavior in which theUE determines, based on information for identifying one NW slicereceived in the rejection notification for the first PDU sessionestablishment request, information for identifying the multipleassociated NW slices to prohibit reconnection to the multiple associatedNW slices, based on the information for identifying the one NW slice.Specifically, the twelfth behavior may be a behavior in which the UEderives information for identifying another NW slice associated withinformation for identifying a NW slice notified in the first PDU sessionestablishment request rejection, based on the network slice associationrule. Note that the network slice association rule may be preconfiguredfor the UE, or may be notified from the network in the rejectionnotification for the PDU session establishment.

A thirteenth 13 behavior in the present embodiment may be a behavior inwhich in a case that multiple different congestion controls areactivated for one or multiple PDU session establishments by the same UE,and multiple timers are provided from the network, the UE manages thetimers, based on the back-off timer priority management rule. Forexample, the first PDU session establishment request of a combination ofa DNN_1 and a slice_1 by the UE is a congestion control target based onboth the DNN and the slice information, and the UE receives the firsttimer #1. Furthermore, the UE makes a second PDU session establishmentrequest for the combination of the DNN_1 and a slice_2, which is acongestion control target based on only the DNN, and receives the firsttimer #2. At this time, in the UE, a behavior of PDU sessionreestablishment by the UE may be managed by the prioritized first timer#2, based on the back-off timer priority management rule. Specifically,the value of the timer held by the UE may be overwritten with the timervalue generated by the prioritized congestion control.

A fourteenth behavior in the present embodiment may be a behavior inwhich in a case that multiple different congestion controls are appliedto one or multiple PDU session establishments by the same UE, andmultiple timers are provided from the network, the UE manages the timerfor each session management instance (PDU session unit). For example,the first PDU session establishment of a combination of a DNN #1 and aslice #1 by the UE is a congestion target, based on both the DNN and theslice information, and the UE manages a back-off timer value of interestas the first timer #1. After that, in a case that in a case that the UEfurther attempts PDU session establishment as the second PDU session forthe combination of the DNN #1 and a slice #2, a congestion target basedon only the DNN is determined, the UE manages the back-off timer valueof interest as the first timer #2. At this time, the UE simultaneouslymanages the multiple timers (here, the first timer #1 and the firsttimer #2). Specifically, the UE manages the timers in units of sessionmanagement instance/PDU session. In a case that the UE simultaneouslyreceives multiple timers in one session management procedure, the UEsimultaneously manages the back-off timers of interest in the congestioncontrol unit identified by the UE.

A fifteenth behavior in the present embodiment may be a behavior inwhich the UE_A 10 performs a first identification process and a secondidentification process, the first identification process being toidentify which type of congestion control is applied among the first tofourth congestion controls, the second identification process being toidentify the DNN and/or the S-NSSAI associated with the congestioncontrol to apply. Note that the first identification process may performidentification, based on at least one or more pieces of identificationinformation of the first identification information to fourthidentification information, and/or at least one or more pieces ofidentification information of the eleventh identification information toeighteenth identification information. Similarly, the secondidentification process may perform identification, based on at least oneor more pieces of identification information of the first identificationinformation to fourth identification information, and/or at least one ormore pieces of identification information of the eleventh identificationinformation to eighteenth identification information.

An example of the first identification process will be described below.In the first identification process, the type of congestion control toapply in a case that any one or a combination of more than two of thefollowing cases are met may be identified as the first congestioncontrol.

-   -   A case that at least the fifteenth identification information is        a value corresponding to the first congestion control.    -   A case that at least the sixteenth identification information is        a value corresponding to the first congestion control.    -   A case that at least the fourteenth identification information        includes information indicating the first congestion control.    -   A case that at least the seventeenth identification information        includes only the DNN and does not include the S-NSSAI.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the first congestion control and the        second congestion control, and is information that only a value        corresponding to the second congestion control can be configured        for the sixteenth identification information.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the first congestion control and the        fourth congestion control, and is information that only a value        corresponding to the fourth congestion control can be configured        for the sixteenth identification information.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the first congestion control, the second        congestion control, and the fourth congestion control, and is        information that only values corresponding to the second        congestion control and the fourth congestion control can be        configured for the sixteenth identification information.

However, the example described above is not a limitation, and the UE_A10 may perform identification, based on at least one or more pieces ofidentification information of the first identification information tofourth identification information, and/or at least one or more pieces ofidentification information of the eleventh identification information toeighteenth identification information, or a combination of two or morepieces of the identification information.

In the first identification process, the type of congestion control toapply in a case that any one or a combination of more than two of thefollowing cases are met may be identified as the second congestioncontrol.

-   -   A case that at least the fifteenth identification information is        a value corresponding to the second congestion control.    -   A case that at least the sixteenth identification information is        a value corresponding to the second congestion control.    -   A case that at least the fourteenth identification information        includes information indicating the second congestion control.    -   A case that at least the seventeenth identification information        includes only the S-NSSAI and does not include the DNN.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the first congestion control and the        second congestion control, and is information that only a value        corresponding to the first congestion control can be configured        for the sixteenth identification information.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the second congestion control and the        third congestion control, and is information that only a value        corresponding to the third congestion control can be configured        for the sixteenth identification information.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the second congestion control, the third        congestion control, and the fourth congestion control, and is        information that only values corresponding to the third        congestion control and the fourth congestion control can be        configured for the sixteenth identification information.

However, the example described above is not a limitation, and the UE_A10 may perform identification, based on at least one or more pieces ofidentification information of the first identification information tofourth identification information, and/or at least one or more pieces ofidentification information of the eleventh identification information toeighteenth identification information, or a combination of two or morepieces of the identification information.

In the first identification process, the type of congestion control toapply in a case that any one or more than two combinations of thefollowing cases are met may be identified as the third congestioncontrol.

-   -   A case that at least the fifteenth identification information is        a value corresponding to the third congestion control.    -   A case that at least the sixteenth identification information is        a value corresponding to the third congestion control.    -   A case that at least the fourteenth identification information        includes information indicating the third congestion control.    -   A case that at least the fifteenth identification information is        a value corresponding to the multiple congestion controls        including the third congestion control and not including the        fourth congestion control, and the seventeenth identification        information includes the S-NSSAI and the DNN.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the third congestion control and the        fourth congestion control, and is information that only a value        corresponding to the fourth congestion control can be configured        for the sixteenth identification information.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the second congestion control and the        third congestion control, and is information that only a value        corresponding to the second congestion control can be configured        for the sixteenth identification information.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the second congestion control, the third        congestion control, and the fourth congestion control, and is        information that only values corresponding to the second        congestion control and the fourth congestion control can be        configured for the sixteenth identification information.

However, the example described above is not a limitation, and the UE_A10 may perform identification, based on at least one or more pieces ofidentification information of the first identification information tofourth identification information, and/or at least one or more pieces ofidentification information of the eleventh identification information toeighteenth identification information, or a combination of two or morepieces of the identification information.

In the first identification process, the type of congestion control toapply in a case that any one or more than two combinations of thefollowing cases are met may be identified as the fourth congestioncontrol.

-   -   A case that at least the fifteenth identification information is        a value corresponding to the fourth congestion control.    -   A case that at least the sixteenth identification information is        a value corresponding to the fourth congestion control.    -   A case that at least the fourteenth identification information        includes information indicating the fourth congestion control.    -   A case that at least the fifteenth identification information is        a value corresponding to the multiple congestion controls        including the fourth congestion control and not including the        third congestion control, and the seventeenth identification        information includes the S-NSSAI and the DNN.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the third congestion control and the        fourth congestion control, and is information that only a value        corresponding to the third congestion control can be configured        for the sixteenth identification information.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the second congestion control and the        fourth congestion control, and is information that only a value        corresponding to the second congestion control can be configured        for the sixteenth identification information.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the first congestion control and the        fourth congestion control, and is information that only a value        corresponding to the first congestion control can be configured        for the sixteenth identification information.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the second congestion control, the third        congestion control, and the fourth congestion control, and is        information that only values corresponding to the second        congestion control and the third congestion control can be        configured for the sixteenth identification information.    -   A case that at least the sixteenth identification information is        not received in a case that the sixteenth identification        information is information for identifying the identification        information for any of the first congestion control, the second        congestion control, and the fourth congestion control, and is        information that only values corresponding to the first        congestion control and the second congestion control can be        configured for the sixteenth identification information.

However, the example described above is not a limitation, and the UE_A10 may perform identification, based on at least one or more pieces ofidentification information of the first identification information tofourth identification information, and/or at least one or more pieces ofidentification information of the eleventh identification information toeighteenth identification information, or a combination of two or morepieces of the identification information, and may perform identificationusing other means.

As described above, the type of congestion control may be identified bythe first identification process.

Next, an example of the second identification process will be describedbelow. Note that the second identification process may be a process toidentify the DNN and/or the S-NSSAI corresponding to the type ofcongestion control identified by the first identification process.

More specifically, the DNN corresponding to the first congestioncontrol, the third congestion control, or the fourth congestion controlmay be determined based on the twelfth identification information.And/or the DNN corresponding to the first congestion control, the thirdcongestion control, or the fourth congestion control may be determinedbased on the seventeenth identification information. And/or the DNNcorresponding to the first congestion control, the third congestioncontrol, or the fourth congestion control may be determined based on thesecond identification information.

Accordingly, the DNN corresponding to the first congestion control, thethird congestion control, or the fourth congestion control may be theDNN indicating the twelfth identification information. And/or the DNNcorresponding to the first congestion control, the third congestioncontrol, or the fourth congestion control may be the DNN included in theseventeenth identification information. And/or the DNN corresponding tothe first congestion control, the third congestion control, or thefourth congestion control may be the DNN indicating the secondidentification information.

Also, the S-NSSAI corresponding to the second congestion control, thethird congestion control, or the fourth congestion control may bedetermined based on the seventeenth identification information. And/orthe DNN corresponding to the first congestion control, the thirdcongestion control, or the fourth congestion control may be determinedbased on the first identification information.

Thus, the DNN corresponding to the first congestion control, the thirdcongestion control, or the fourth congestion control may be the S-NSSAIindicating the seventeenth identification information. And/or the DNNcorresponding to the first congestion control, the third congestioncontrol, or the fourth congestion control may be the S-NSSAI included inthe first identification information.

However, the example described above is not a limitation, and the UE_A10 may perform identification, based on at least one or more pieces ofidentification information of the first identification information tofourth identification information, and/or at least one or more pieces ofidentification information of the eleventh identification information toeighteenth identification information, or a combination of two or morepieces of the identification information, and may perform identificationusing other means.

Based on the fifteenth behavior described above, the UE_A 10 mayidentify the congestion control which the core network_B 190 applies tothe UE_A 10. In other words, the UE_A 10 may identify, as the congestioncontrol to apply, the corresponding type of congestion control and thecorresponding S-NSSAI and/or DNN, based on the fifteenth behavior. Notethat the UE_A 10 may store and manage one or multiple pieces ofidentification information of the first identification information tofourth identification information and the eleventh identificationinformation to eighteenth identification information in association withthe congestion control to apply. Here, the third identificationinformation and/or the fourth identification information and/or thethirteenth identification information may be stored and managed asinformation identifying the congestion control to apply.

A sixteenth behavior in the present embodiment is a behavior in which ina case that a NW-initiated session management procedure is performed ina state where the UE runs the first timer, the UE stops the first timer.

Here, for example, the sixteenth behavior may be a behavior in which ina case that the multiple first timers are running, the UE determines andstops the first timer to stop among the multiple running first timers,based on 21st identification information. And/or the sixteenth behaviormay be a behavior in which the UE stops the first timer associated witha congestion control identified by a seventeenth behavior. Note that ina case of multiple congestion controls identified by the seventeenthbehavior, the timers associated with the respective congestion controlsmay be stopped.

The seventeenth behavior in the present embodiment may be a behavior ofthe UE identifying a congestion control of which application is to stopamong one or multiple congestion controls that the UE applies, based onthe reception of the control message transmitted by the core network.For example, the UE may identify the congestion control of whichapplication is to stop or change based on the 21st identificationinformation.

Specifically, as described above, the UE stores the third identificationinformation and/or the fourth identification information and/or thethirteenth identification information or the like in the fourth processas information identifying the congestion control, and may identify, asthe congestion control of which application is to stop, the congestioncontrol in which these identification information identifying thecongestion control and the thirteenth identification informationincluded in the 21st identification information match.

And/or, the UE may identify the congestion control of which applicationis to stop, based on one of or a combination of multiple pieces of theeleventh identification information to eighteenth identificationinformation included in the 21st identification information. Here, thedetails of the identification method may be similar to theidentification process in the fifteenth behavior described in the fourthprocess in the example of the PDU session establishment proceduredescribed below. That is, the UE may identify the congestion control tostop, by the method similar to a method for identifying the congestioncontrol to apply.

Note that the UE may identify multiple congestion controls of whichapplication is to stop. Hereinafter, the congestion control identifiedby the method described above is referred to as a first congestioncontrol, and a method for identifying a second congestion controldifferent from the first congestion control will be described.

For example, the UE may identify as a second congestion control acongestion control associated with a DNN that is the same as the DNNassociated with the first congestion control. And/or the UE may identifyas the second congestion control a congestion control associated with aS-NSSAI that is the same as the S-NSSAI associated with the firstcongestion control. Note that identifying the multiple congestioncontrols of which application is to stop may be configured to beperformed only in a case that the first congestion control and/or thesecond congestion control are particular types of congestion control.

Specifically, in a case that the first congestion control is any of thefirst to fourth congestion controls, the UE may identify the secondcongestion control. And/or, in identifying the second congestioncontrol, the UE may identify the second congestion control in a casethat a congestion control to search for is any of the first to fourthcongestion controls. Note that the type of congestion control in whichthe first congestion control and/or the second identificationinformation can identify multiple congestion controls may bepreconfigured for the core network and/or the UE. Note that the numberof particular types of congestion controls for which identification isallowed need not be limited to one, and multiple types may beconfigured.

The first identification information in the present embodiment isinformation identifying belonging to the first NW slice. In other words,the first identification information may be information indicating thatthe UE desires to establish a PDU session belonging to the first NWslice. Specifically, the first identification information may beinformation for identifying the first NW slice. Note that the sliceinformation may be identification information indicating a specificS-NSSAI. Note that the first identification information may beinformation identifying a particular NW slice within the operator A'snetwork, or may be information identifying the same NW slice commonlyalso in the operator B (other operators than the operator A).Furthermore, the first identification information may be information foridentifying the first NW slice configured from the HPLMN, may beinformation for identifying the first NW slice acquired from the AMF inthe registration procedure, or may be information for identifying thefirst NW slice allowed from the network. Furthermore, the firstidentification information may be information for identifying the firstNW slice stored for each PLMN.

The second identification information in the present embodiment may be aData Network Name (DNN) and information used for identifying a DataNetwork (DN).

The third identification information in the present embodiment may be aPDU Session ID or information used for identifying a PDU Session.

The fourth identification information in the present embodiment may be aProcedure transaction identity (PTI), or information which may identifytransmission and/or reception of a series of messages of a particularsession management procedure as a single group, and further, may be usedto identify and/or distinguish the transmission and/or reception of aseries of messages from transmission and/or reception of another seriesof session management related messages.

The eleventh identification information in the present embodiment may beinformation indicating that a request for PDU session establishment or arequest for PDU session modification is rejected. Note that a requestfor PDU session establishment or a request for PDU session modificationis a request made by the UE, and includes the DNN and/or the S-NSSAI.Specifically, the eleventh identification information may be informationindicating that the NW rejects a request for establishment ormodification of a PDU session corresponding to these DNN and/or S-NSSAI.

The eleventh identification information may be information indicatingre-attempt (Re-attempt) information.

The NW may indicate to the UE the congestion control by transmitting atleast one identification information of the twelfth identificationinformation to eighteenth identification information along with theeleventh identification information to the UE. In other words, the NWmay notify the UE of the congestion control corresponding to one of or acombination of multiple pieces of identification information of thetwelfth identification information to eighteenth identificationinformation. On the other hand, the UE may identify the congestioncontrol corresponding to one of or a combination of multiple pieces ofidentification information of the twelfth identification information toeighteenth identification information, and perform a process based onthe identified congestion control. Specifically, the UE may start tocount the first timer associated with the identified congestion control.Note that the timer value of the first timer may be determined by use ofthe fourteenth identification information, configured with a timer valuethat is configured in another manner such as one using a value prestoredby the UE, or configured with a random value.

The twelfth identification information in the present embodiment may bea DNN, which may be a DNN not allowed by the network, or informationindicating that a DNN identified by the second identificationinformation is not allowed. Furthermore, the twelfth identificationinformation may be a DNN the same as that of the second identificationinformation.

The thirteenth identification information in the present embodiment maybe a PDU session ID and/or a PTI, which may be a PDU session ID and/or aPTI not allowed by the network, or information indicating that a PDUsession ID and/or a PTI identified by the third identificationinformation is not allowed. The PDU session ID of the thirteenthidentification information may be a PDU session ID the same as the thirdidentification information. The PTI of the thirteenth identificationinformation may be a PTI the same as the fourth identificationinformation.

Here, the thirteenth identification information may be used asinformation for identifying a congestion control of which the UE isnotified by the NW based on the rejection of the PDU sessionestablishment. In other words, the UE may store and manage thethirteenth identification information in association with the congestioncontrol performed based on the fifteenth behavior to use the thirteenthidentification information as information for identifying the performedcongestion control. Note that the information identifying the congestioncontrol may include a combination of one or more of the fourteenthidentification information to eighteenth identification information withthe thirteenth identification information.

The fourteenth identification information in the present embodiment maybe information indicating a value of the back-off timer. In other words,the back-off timer may be a value indicating an effective period of thecongestion control of which the UE is notified by the NW based on therejection of the PDU session establishment. In other words, the UE mayuse the fourteenth identification information as the timer value in thefifteenth behavior that is performed in response to the reception of thefourteenth identification information. Furthermore, the fourteenthidentification information may include information identifying the typeof congestion control in addition to the timer value. Specifically,information identifying which of the first to fourth congestion controlsis the relevant congestion control may be included. For example, theinformation identifying the type of congestion control may be a timername identifying each congestion control, or may be a flag identifyingeach congestion control. This is not a limitation, and the type ofcongestion control may be identified in other manners such as beingidentified by the location stored in the control message, and the like.

The fifteenth identification information in the present embodiment isinformation indicating one or more Cause Values indicating the causes ofthe rejection of the present procedure. In other words, the cause valuemay be information indicating the congestion control applied to thepresent procedure by the NW, or may be information indicating a causevalue for rejecting the present procedure applied by the NW other thancongestion control.

Note that the cause value may be information for identifying whichcongestion control of the first to fourth congestion controls isindicated by the congestion control of which the NW notifies the UE,based on the rejection of the PDU session establishment. In this case,depending on each congestion control of the first to fourth congestioncontrols, the NW may transmit a different value as a cause value to theUE. The UE may know the meaning of each value transmitted as the causevalue in advance to identify which of the first to fourth congestioncontrols is the relevant congestion control, in the fifteenth behavior,based on at least the fifteenth identification information.

Alternatively, the cause value may be information for identifyingwhether the congestion control of which the NW notifies the UE, based onthe rejection of the PDU session establishment is the first congestioncontrol or any congestion control of the second congestion control, thethird congestion control, and the fourth congestion control. In thiscase, the NW may transmit different values as the cause values to the UEdepending on the case of the first congestion control and the case ofany congestion control of the second congestion control, the thirdcongestion control, and the fourth congestion control. The UE may knowthe meaning of each value transmitted as the cause value in advance toidentify whether the first congestion control or any congestion controlof the second congestion control, the third congestion control, and thefourth congestion control, in the fifteenth behavior, based on at leastthe fifteenth identification information.

Alternatively, the cause value may be information for identifyingwhether the congestion control of which the NW notifies the UE, based onthe rejection of the PDU session establishment is the first congestioncontrol, the second congestion control, or any congestion control of thethird congestion control and the fourth congestion control. In thiscase, the NW may transmit different values as the cause values to the UEdepending on the case of the first congestion control, the case of thesecond congestion control, and the case of any congestion control of thethird congestion control and the fourth congestion control. The UE mayknow the meaning of each value transmitted as the cause value in advanceto identify whether the first congestion control, the second congestioncontrol, or any congestion control of the third congestion control andthe fourth congestion control, in the fifteenth behavior, based on atleast the fifteenth identification information.

Alternatively, the cause value may be information for identifyingwhether the congestion control of which the NW notifies the UE, based onthe rejection of the PDU session establishment is the first congestioncontrol or the second congestion control, or the third congestioncontrol or the fourth congestion control. In this case, the NW maytransmit different values as the cause values to the UE depending on thecase of the first congestion control or the second congestion control,and the case of the third congestion control or the fourth congestioncontrol. The UE may know the meaning of each value transmitted as thecause value in advance to identify whether the first congestion controlor the second congestion control, or the third congestion control or thefourth congestion control, in the fifteenth behavior, based on at leastthe fifteenth identification information.

Alternatively, the cause value may be information for identifyingwhether the congestion control of which the NW notifies the UE, based onthe rejection of the PDU session establishment is the second congestioncontrol or the third congestion control, or the first congestion controlor the fourth congestion control. In this case, the NW may transmitdifferent values as the cause values to the UE depending on the case ofthe second congestion control or the third congestion control, and thecase of the first congestion control or the fourth congestion control.The UE may know the meaning of each value transmitted as the cause valuein advance to identify whether the second congestion control or thethird congestion control, or the first congestion control or the fourthcongestion control, in the fifteenth behavior, based on at least thefifteenth identification information.

Alternatively, the cause value may be information for identifyingwhether the congestion control of which the NW notifies the UE, based onthe rejection of the PDU session establishment is the second congestioncontrol or the fourth congestion control, or the first congestioncontrol or the third congestion control. In this case, the NW maytransmit different values as the cause values to the UE depending on thecase of the second congestion control or the fourth congestion control,and the case of the first congestion control or the third congestioncontrol. The UE may know the meaning of each value transmitted as thecause value in advance to identify whether the second congestion controlor the fourth congestion control, or the first congestion control or thethird congestion control, in the fifteenth behavior, based on at leastthe fifteenth identification information.

Alternatively, the cause value may be information indicating that the NWperforms the congestion control for the UE, based on the rejection ofthe PDU session establishment. In other words, the cause value may beinformation for causing any of the first to fourth congestion controlsto be performed for the UE. In this case, the cause value may not beinformation that can identify a particular congestion control.

Furthermore, a more detailed example of the above-described cause valuefor rejecting the present procedure applied by the NW other thancongestion control may be a cause value of which the NW notifies the UE,indicating that an external DN rejected the present procedure becausethe DNN information is not included in the present procedure or becauseof the unknown DNN (Missing or unknown DNN). The more detailed examplemay be a cause value of which the NW notifies the UE, indicating thatthe external DN rejected the present procedure because the PDU sessiontype of the present procedure cannot be recognized or is not allowed(Unknown PDU session type). The more detailed example may be a causevalue of which the NW notifies the UE, indicating that the external DNrejected the present procedure because of a failure of userauthentication and authorization in the present procedure, or a revokeof authentication and authorization by the external DN, or a revoke ofauthentication and authorization by the NW (User authentication orauthorization failed). The more detailed example may be a cause value ofwhich the NW notifies the UE, indicating that the requested service oroperation or the request for resource reservation was rejected due tounspecified reasons (Request rejected, unspecified). The more detailedexample may be a cause value of which the NW notifies the UE, indicatingthat the NW cannot temporarily receive the service request from the UE(Service option temporarily out of order). The more detailed example maybe a cause value of which the NW notifies the UE, indicating that thePTI inserted by the UE is already in use (PTI already in use). The moredetailed example may be a cause value of which the NW notifies the UE,indicating that the UE is out of the LADN service area (Out of LADNservice area). The more detailed example may be a cause value of whichthe NW notifies the UE, indicating that only PDU session type IPv4 isallowed (PDU session type IPv4 only allowed). The more detailed examplemay be a cause value of which the NW notifies the UE, indicating thatonly PDU session type IPv6 is allowed (PDU session type IPv6 onlyallowed). The more detailed example may be a cause value of which the NWnotifies the UE, indicating that the NW does not have the PDU session ofinterest in a case that the UE transfers the PDU session from thenon-3GPP access to the 3GPP access or from the EPS to the 5GS (PDUsession does not exist). The more detailed example may be a cause valueof which the NW notifies the UE, indicating that the NW does not supportthe SSC mode requested by the UE (Not supported SSC mode). The moredetailed example may be a cause value of which the NW notifies the UE,indicating that the external DN rejected the present procedure becausethe DNN information is not included in the present procedure via aparticular slice or because of the unknown DNN (Missing or unknown DNNin a slice). The more detailed example may be a cause value of which theNW notifies the UE, indicating that the UE does not satisfy therequirement of the maximum data transfer rate for user-plane integrityprotection that is required in the service requested by the UE to the NW(Maximum data rate per UE for user-plane integrity protection is toolow).

Note that in the present embodiment, in a case that the third congestioncontrol is not performed, the meaning described above corresponding tothe third congestion control in the cause value for the fifteenthidentification information is unnecessary, and the cause value for thefifteenth identification information may be that in which the process,description, and meaning of the third congestion control are omittedfrom the description above. Note that in the present embodiment, in acase that the fourth congestion control is not performed, the meaningdescribed above corresponding to the fourth congestion control in thecause value for the fifteenth identification information is unnecessary,and the cause value for the fifteenth identification information may bethat in which the process, description, and meaning of the fourthcongestion control are omitted from the description above.

As a more detailed example, the fifteenth identification informationidentifying the first congestion control may be a cause value indicatingthat the resources are insufficient (Insufficient resources). Thefifteenth identification information identifying the second congestioncontrol may be a cause value indicating that the resources for specificslice are insufficient (Insufficient resources for specific slice). Thefifteenth identification information identifying the third congestioncontrol may be a cause value indicating that the resources for specificslice and DNN are insufficient (Insufficient resources for specificslice and DNN).

In this way, the fifteenth identification information may be informationcapable of identifying the type of congestion control, and further, maybe information indicating which type of congestion control the back-offtimer and/or the back-off timer value indicated by the fourteenthidentification information corresponds to.

Accordingly, the UE_A 10 may identify the type of congestion control,based on the fifteenth identification information. Furthermore, whichtype of congestion control the back-off timer and/or the back-off timervalue indicated by the fourteenth identification information correspondsto may be determined based on the fifteenth identification information.

The sixteenth identification information in the present embodiment isone or more pieces of identifier (Indication) information indicatingthat the present procedure is rejected. In other words, the Indicationinformation may be information indicating the congestion control appliedto the present procedure by the NW. The NW may indicate the congestioncontrol applied by the NW, based on the sixteenth identificationinformation.

For example, the Indication information may be information indicatingwhether or not which congestion control of two or more congestioncontrols among the first to fourth congestion controls is regulated withrespect to the UE by the NW. Accordingly, the NW may transmit a valueassociated with regulation management applied to the UE, as Indicationinformation. The UE may know the meaning of each value transmitted asthe Indication information in advance to identify which of the first tofourth congestion controls is the relevant congestion control, in thefifteenth behavior, based on at least the sixteenth identificationinformation. Here, the two or more congestion controls among the firstto fourth congestion controls are congestion controls that can beidentified using the Indication information, and the congestion controlsto be identified may be all four congestion controls, the first andsecond congestion controls, the third and fourth congestion controls,the second to fourth congestion controls, or any other combinationsthereof.

Note that the Indication information does not necessarily require valuescorresponding to the all respective congestion controls to beidentified. For example, in a case that the congestion controls exceptfor a congestion control A are assigned and associated with the valuesof the Indication information, the congestion control A may not benecessarily configured with the value of the Indication information. Inthis case, the NW and the UE can identify that the congestion control Ais the first congestion control because the Indication information notbeing transmitted and/or received. Note that the congestion control Amay be any congestion control of the first to fourth congestioncontrols.

In addition, in a case of notifying the UE of the congestion control,based on the transmission of the PDU session establishment rejectmessage, there may be a case that Identification is included and a casethat Identification is not included, depending on the type of congestioncontrol of the first to fourth congestion controls. In other words,depending on the type of congestion control, the NW may use theIdentification information as information indicating the congestioncontrol, or may use another piece of identification information asinformation indicating the congestion control, without using theIdentification information, in accordance with the type of congestioncontrol.

Note that in the present embodiment, in a case that the third congestioncontrol is not performed, the meaning described above corresponding tothe third congestion control in the Indication information for thesixteenth identification information is unnecessary, and the Indicationinformation for the sixteenth identification information may be that inwhich the process, description, and meaning of the third congestioncontrol are omitted from the description above. In the presentembodiment, in a case that the fourth congestion control is notperformed, the meaning described above corresponding to the fourthcongestion control in the Indication information for the sixteenthidentification information is unnecessary, and the Indicationinformation for the sixteenth identification information may be that inwhich the process, description, and meaning of the fourth congestioncontrol are omitted from the description above.

The seventeenth identification information in the present embodiment isone or more pieces of Value information indicating that the presentprocedure is rejected. In other words, the Value information may beinformation indicating the congestion control applied to the presentprocedure by the NW. Note that the seventeenth identificationinformation may be information including at least one of identificationinformation for identifying one or multiple NW slices included in theeighteenth identification information, and/or the twelfth identificationinformation.

The NW may indicate the congestion control applied by the NW, based onthe seventeenth identification information. In other words, the NW mayindicate which congestion control of the first to fourth congestioncontrols is applied, based on the seventeenth identificationinformation. Furthermore, the NW may indicate the DNN and/or the S-NSSAIthat is a target of the congestion control applied to the UE based onthe transmission of the PDU session reject message, based on theseventeenth identification information. For example, in a case that theseventeenth identification information is the DNN #1 only, the NW mayindicate that the first congestion control associated with the DNN #1 isapplied. In a case that the seventeenth identification information isthe S-NSSAI #1 only, the NW may indicate that the second congestioncontrol associated with the S-NSSAI #1 is applied. In a case that theseventeenth information includes the DNN #1 and the S-NSSAI #1, the NWmay indicate that the third congestion control or the fourth congestioncontrol associated with at least one of the DNN #1 and/or the S-NSSAI #1is applied.

Note that the seventeenth identification information is not necessarilythe information that can identify which congestion control of the firstto fourth congestion controls is applied, and the seventeenthidentification information may be information indicating the DNN and/orthe S-NSSAI that is a target of the congestion control identified byother means, such as being identified based on another piece ofidentification information.

The eighteenth identification information in the present embodiment maybe information indicating that a request for establishment of a PDUsession belonging to the first NW slice is rejected, or informationindicating that a request for establishment or modification of a PDUsession belonging to the first NW slice is not allowed. Here, the firstNW slice may be a NW slice determined by the first identificationinformation, or a different NW slice. The eighteenth identificationinformation may be information indicating that establishment of a PDUsession belonging to the first NW slice is not allowed in the DNidentified by the twelfth identification information, or informationindicating that establishment of a PDU session belonging to the first NWslice is not allowed in the PDU session identified by the thirteenthidentification information. Furthermore, the eleventh identificationinformation may be information indicating that establishment of a PDUsession belonging to the first slice is not allowed in a registrationarea and/or tracking area to which the UE_A 10 currently belongs, orinformation indicating that establishment of a PDU session belonging tothe first NW slice is not allowed in an access network to which the UE_A10 is connected. Furthermore, the eleventh identification informationmay be identification information for identifying one or multiple NWslices determining a NW slice to which a rejected PDU session requestbelongs. Furthermore, the eighteenth identification information may beidentification information indicating the auxiliary information for theradio access system to select the appropriate MME in a case that the UEswitches the connection destination to the EPS. Note that the auxiliaryinformation may be information indicating the DCN ID. Furthermore, theeighteenth identification information may be the network sliceassociation rule that is a rule for associating multiple pieces ofnetwork slice information.

The 21st identification information in the present embodiment may beinformation to stop one or multiple first timers run by the UE, or maybe information indicating a first timer to stop among the first timersrun by the UE. Specifically, the 21st identification information may beinformation indicating the thirteenth identification information storedin the UE in association with the first timer. Furthermore, the 21stidentification information may be information indicating at least one ofthe twelfth identification information to eighteenth identificationinformation stored in the UE in association with the first timer.

Furthermore, the 21st identification information may be information tochange the association between the first timer stored in the UE andinformation indicating at least one of the thirteenth identificationinformation to seventeenth identification information. For example, in acase that the first timer that prohibits a UE-initiated sessionmanagement for a combination of DNN #A and S-NSSAI #A is running, in acase of receiving a NW-initiated session management request includingthe 21st identification information that allows connection to the DNN#A, the UE may change the association with the running timer to onlywith the S-NSSAI #A, and may recognize that the UE-initiated sessionmanagement request to the DNN #A is allowed. In other words, the 21stidentification information may be information indicating that thecongestion control applied at the time of receiving the 21stidentification information is changed to another congestion controlamong the first to fourth congestion controls.

Next, the initial procedure according to the present embodiment will bedescribed using FIG. 9. Hereinafter, the initial procedure is alsoreferred to as the present procedure, and the present procedure includesthe Registration procedure, the UE-initiated PDU session establishmentprocedure, and the network-initiated session management procedure.Details of the registration procedure, the PDU session establishmentprocedure, and the network-initiated session management procedure willbe described later.

Specifically, each apparatus performs the registration procedure (S900),and thereby, the UE_A 10 transitions to a state of being registered inthe network (RM-REGISTERED state). Next, by performing the PDU sessionestablishment procedure by each apparatus (S902), the UE_A 10establishes the PDU session with the DN_A 5 that provides the PDUconnection service, via the core network_B 190 and transitions to thefirst state (S904). Note that the PDU session is assumed to beestablished via the access network and the UPF_A 235, but is not limitedthereto. That is, a UPF (UPF_C 239) different from the UPF_A 235 may bepresent between the UPF_A 235 and the access network. At this time, thePDU session is established via the access network, the UPF_C 239, andthe UPF_A 235. Next, each apparatus in the first state may perform thenetwork-initiated session management procedure at any timing (S906).

Note that each apparatus may exchange various pieces of capabilityinformation and/or various pieces of request information of eachapparatus in the registration procedure and/or the PDU sessionestablishment procedure and/or the network-initiated session managementprocedure. Note that in a case that each apparatus performs the exchangeof various pieces of information and/or negotiation of various requestsin the registration procedure, each apparatus may or need not performthe exchange of various pieces of information and/or the negotiation ofvarious requests in the PDU session establishment procedure and/or thenetwork-initiated session management procedure. In a case that eachapparatus does not perform the exchange of various pieces of informationand/or the negotiation of various requests in the registrationprocedure, each apparatus may perform the exchange of various pieces ofinformation and/or the negotiation of various requests in the PDUsession establishment procedure and/or the network-initiated sessionmanagement procedure. Even in a case that each apparatus performs theexchange of various pieces of information and/or the negotiation ofvarious requests in the registration procedure, each apparatus mayperform the exchange of various pieces of information and/or thenegotiation of various requests in the PDU session establishmentprocedure and/or the network-initiated session management procedure.

In addition, each apparatus may perform the PDU session establishmentprocedure in the registration procedure or after the registrationprocedure is completed. Furthermore, in a case that the PDU sessionestablishment procedure is performed in the registration procedure, thePDU session establishment request message included in the registrationrequest message may be transmitted and/or received, and the PDU sessionestablishment accept message included in the registration accept messagemay be transmitted and/or received, a PDU session establishment completemessage included in a registration complete message may be transmittedand/or received, and a PDU session establishment reject message includedin a registration reject message may be transmitted and/or received. Ina case that the PDU session establishment procedure is performed in theregistration procedure, each apparatus may establish a PDU session,based on the completion of the registration procedure, or may transitionto the state where the PDU session is established between theapparatuses.

Furthermore, each apparatus involved in the present procedure maytransmit and/or receive each control message described in the presentprocedure to transmit and/or receive one or more pieces ofidentification information included in each control message and storeeach piece of identification information transmitted and/or received asa context.

1.3.1. Overview of Registration Procedure

First, the following describes the overview of the registrationprocedure. The registration procedure is a procedure initiated by theUE_A 10 to register to the network (the access network, and/or the corenetwork_B 190, and/or the DN_A 5). In a state in which the UE_A 10 isnot registered in the network, the UE_A 10 can perform the presentprocedure at any timing such as the timing of turning on power. In otherwords, the UE_A 10 may initiate the present procedure at any timing in anon-registered state (RM-DEREGISTERED state). In addition, eachapparatus may transition to a registered state (RM-REGISTERED state),based on the completion of the registration procedure.

Furthermore, the present procedure may be a procedure for updatinglocation registration information of the UE_A 10 in the network, forregularly notifying a state of the UE_A 10 from the UE_A 10 to thenetwork, and/or for updating particular parameters related to the UE_A10 in the network.

The UE_A 10 may initiate the present procedure in a case that the UE_A10 applies mobility across TAs. In other words, the UE_A 10 may initiatethe present procedure in a case that the UE_A 10 moves to a TA differentfrom a TA indicated in a TA list that the UE_A 10 holds. Furthermore,the UE_A 10 may initiate the present procedure in a case that a runningtimer expires. The UE_A 10 may initiate the present procedure in a casethat a context of each apparatus needs to be updated due todisconnection or invalidation (also referred to as deactivation) of aPDU session. Furthermore, the UE_A 10 may initiate the present procedurein a case that a change occurs in capability information and/orpreference concerning PDU session establishment of the UE_A 10.Furthermore, the UE_A 10 may initiate the present procedure regularly.Note that, besides the above, the UE_A 10 can perform the presentprocedure at any timing as long as a PDU session is established.

1.3.1.1. Example of Registration Procedure

An example procedure of performing the registration procedure will bedescribed with reference to FIG. 10. In this section, the presentprocedure refers to the registration procedure. Each step of the presentprocedure will be described below.

First, the UE_A 10 transmits a Registration Request message to the AMF_A240 via the NR node (also referred to as the gNB)_A 122 and/or theng-eNB (S1000) (S1002) (S1004) to initiate the registration procedure.In addition, the UE_A 10 may transmit a Session Management (SM) message(e.g., a PDU session establishment request message) included in theregistration request message, or transmit the SM message (e.g., the PDUsession establishment request message) along with the registrationrequest message to initiate a procedure for session management (SM) suchas a PDU session establishment procedure, during the registrationprocedure.

Specifically, the UE_A 10 transmits a Radio Resource Control (RRC)message including the registration request message to the NR node_A 122and/or the ng-eNB (S1000). The NR node_A 122 and/or the ng-eNB, in acase of receiving the RRC message including the registration requestmessage, retrieves the registration request message in the RRC messageand selects the AMF_A 240 as the NF or the common CP function to whichthe registration request message is routed (S1002). Here, the NR node_A122 and/or the ng-eNB may select the AMF_A 240, based on informationincluded in the RRC message. The NR node_A 122 and/or the ng-eNBtransmit or forward the registration request message to the selectedAMF_A 240 (S1004).

Note that the registration request message is a Non-Access-Stratum (NAS)message transmitted and/or received on the N1 interface. The RRC messageis a control message transmitted and/or received between the UE_A 10 andthe NR node_A 122 and/or the ng-eNB. The NAS message is processed in aNAS layer, the RRC message is processed in an RRC layer, and the NASlayer is the higher layer than the RRC layer.

In addition, in a case that there are multiple NSIs requestingregistration, the UE_A 10 may transmit a registration request messagefor each of the NSIs, or may transmit multiple registration requestmessages included in one or more RRC messages. Furthermore, theabove-described multiple registration request messages included in oneor more RRC messages may be transmitted as one registration requestmessage.

The AMF_A 240, in a case of receiving the registration request messageand/or the control message different from the registration requestmessage, performs a first condition determination. The first conditiondetermination is for the AMF_A 240 to determine whether to accept arequest of the UE_A 10. In the first condition determination, the AMF_A240 determines whether the first condition determination is true orfalse. In a case that the first condition determination is true (thatis, in a case that the network accepts the request of the UE_A 10), theAMF_A 240 initiates a procedure (A) in the present procedure, or in acase that the first condition determination is false (that is, in a casethat the network does not accept the request of the UE_A 10), the AMF_A240 initiates a procedure (B) in the present procedure.

As follows, steps in a case that the first condition determination istrue, in other words, each step of the procedure (A) in the presentprocedure will be described. The AMF_A 240 performs a fourth conditiondetermination, and initiates the procedure (A) in the present procedure.The fourth condition determination is for the AMF_A 240 to determinewhether to transmit and/or receive an SM message to and/or from theSMF_A 230. In other words, the fourth condition determination may be forthe AMF_A 240 to determine whether to perform the PDU sessionestablishment procedure in the present procedure. In a case that thefourth condition determination is true (i.e., in a case that the AMF_A240 is to transmit and/or receive an SM messages to and/or from theSMF_A 230), the AMF_A 240 selects the SMF_A 230, and transmits and/orreceives an SM message to and/or from the selected SMF_A 230, or in acase that the fourth condition determination is false (i.e., in a casethat the AMF_A 240 does not transmit and/or receive an SM messages toand/or from the SMF_A 230), the AMF_A 240 omits those operations(S1006). Note that in a case that the AMF_A 240 receives an SM messageindicating rejection from the SMF_A 230, the AMF_A 240 may terminate theprocedure (A) in the present procedure, and may initiate the procedure(B) in the present procedure.

In addition, the AMF_A 240 transmits the Registration Accept message tothe UE_A 10 via the NR node_A 122, based on the reception of theregistration request message from the UE_A 10 and/or the completion ofthe transmission and/or reception of the SM message to/from the SMF_A230 (S1008). For example, in the case that the fourth conditiondetermination is true, the AMF_A 240 may transmit the registrationaccept message, based on the reception of the registration requestmessage from the UE_A 10. In the case that the fourth conditiondetermination is false, the AMF_A 240 may transmit the registrationaccept message, based on the completion of the transmission and/orreception of the SM message to and/or from the SMF_A 230. Here, theregistration accept message may be transmitted as a response message tothe registration request message. The registration accept message is aNAS message transmitted and/or received on the N1 interface, and forexample, the AMF_A 240 may transmit a registration accept message as acontrol message of the N2 interface to the NR node_A 122, and the NRnode_A 122 may transmit the received message with being included in theRRC message to the UE_A 10.

In the case that the fourth condition determination is true, the AMF_A240 may transmit an SM message (e.g., a PDU session establishment acceptmessage) with being included in the registration accept message, ortransmit an SM message (e.g., a PDU session establishment acceptmessage) together with the registration accept message. Thistransmission method may be performed in a case that the SM message(e.g., a PDU session establishment request message) is included in theregistration request message, and the fourth condition determination istrue. Furthermore, the transmission method may be performed in a casethat the registration request message and the SM message (e.g., the PDUsession establishment request message) are included and the fourthcondition determination is true. The AMF_A 240 may indicate that theprocedure for SM has been accepted by performing such a transmissionmethod.

The UE_A 10 receives the registration accept message via the NR node_A122 (S1008). The UE_A 10 receives the registration accept message andrecognizes the contents of various types of identification informationincluded in the registration accept message.

Next, the UE_A 10 transmits a Registration Complete message to the AMF_A240, based on the reception of the registration accept message (S1010).Note that, in a case that the UE_A 10 has received an SM message such asa PDU session establishment accept message, the UE_A 10 may transmit theSM message such as the PDU session establishment complete messageincluded in the registration complete message, or may include the SMmessage therein to indicate that the procedure for SM is completed.Here, the registration complete message may be transmitted as a responsemessage to the registration accept message. The registration completemessage is a NAS message transmitted and/or received on the N1interface, and for example, the UE_A 10 may transmit a registrationcomplete message with being included in an RRC message to the NR node_A122, and the NR node_A 122 may transmit the received message as acontrol message of the N2 interface to the AMF_A 240.

The AMF_A 240 receives the registration complete message (S1010). Inaddition, each apparatus completes the procedure (A) in the presentprocedure, based on the transmission and/or reception of theregistration accept message and/or the registration complete message.

Next, steps in the case that the first condition determination is false,that is, the steps in the procedure (B) in the present procedure will bedescribed. The AMF_A 240 transmits a Registration Reject message to theUE_A 10 via the NR node_A 122 (S1012) to initiate the procedure (B) inthe present procedure. Here, the registration reject message may betransmitted as a response message to the registration request message.The registration reject message is a NAS message transmitted and/orreceived on the N1 interface, and for example, the AMF_A 240 maytransmit a registration reject message as a control message of the N2interface to the NR node_A 122, and the NR node_A 122 may transmit thereceived message with being included in the RRC message to the UE_A 10.Further, the registration reject message transmitted by the AMF_A 240 isnot limited thereto as long as it is a message for rejecting the requestof the UE_A 10.

Note that the procedure (B) during the present procedure may beinitiated in a case that the procedure (A) in the present procedure iscanceled. Note that in the case that the fourth condition determinationis true during the procedure (A), the AMF_A 240 may transmit theregistration reject message including an SM message meaning rejectionsuch as a PDU session establishment reject message, or may indicate thatthe procedure for the SM is rejected by including the SM message meaningrejection. In that case, the UE_A 10 may further receive the SM message,such as the PDU session establishment reject message, that indicatesrejection, or may recognize that the procedure for SM has been rejected.

The UE_A 10 may receive the registration reject message, or not receivethe registration accept message, and thereby, recognize that the requestof the UE_A 10 is rejected. Each apparatus completes the procedure (B)in the present procedure, based on the transmission and/or reception ofthe registration reject message.

Each apparatus completes the present procedure (registration procedure),based on the completion of the procedure (A) or (B) in the presentprocedure. Note that each apparatus may transition to a state in whichthe UE_A 10 is registered with the network (RM_REGISTERED state), basedon the completion of the procedure (A) in the present procedure, or maymaintain a state in which the UE_A 10 is not registered with the network(RM_DEREGISTERED state), based on the completion of the procedure (B) inthe present procedure. Transition to each state of each apparatus may beperformed based on completion of the present procedure, or may beperformed based on an establishment of a PDU session.

Furthermore, each apparatus may perform processing, based onidentification information transmitted and/or received in the presentprocedure, based on completion of the present procedure.

Furthermore, the first condition determination may be performed based onidentification information, and/or subscriber information, and/or anoperator policy included in the registration request message. Forexample, the first condition determination may be true in a case thatthe network allows a request of the UE_A 10. In addition, the firstcondition determination may be false in a case that the network does notallow a request of the UE_A 10. Furthermore, the first conditiondetermination may be true in a case that the network of a destination ofregistration of the UE_A 10 and/or an apparatus in the network supportsa function requested by the UE_A 10, and may be false in a case that thenetwork and/or the apparatus does not support the function. The firstcondition determination may be true in a case that the network isdetermined to be in a congested state, or may be false in a casedetermined not to be in a congested state. Note that conditions fordetermining whether the first condition determination is true or falsemay not be limited to the above-described conditions.

The fourth condition determination may also be performed based onwhether the AMF_A 240 has received an SM and may be performed based onwhether an SM message is included in the registration request message.For example, the fourth condition determination may be true in a casethat the AMF_A 240 has received the SM and/or the SM message is includedin the registration request message, and may be false in a case that theAMF_A 240 has not received the SM and/or the SM message is not includedin the registration request message. Note that conditions fordetermining whether the fourth condition determination is true or falsemay not be limited to the above-described conditions.

1.3.2. Overview of PDU Session Establishment Procedure

Next, an overview of the PDU session establishment procedure performedto establish a PDU session with the DN_A 5 will be described. The PDUsession establishment procedure is also referred to as a presentprocedure below. The present procedure is a procedure for each apparatusto establish the PDU session. Note that each apparatus may perform thepresent procedure in a state in which the registration procedure iscompleted or during the registration procedure. In addition, eachapparatus may initiate the present procedure in a registered state, ormay initiate the present procedure at any timing after the registrationprocedure. Each apparatus may establish the PDU session, based oncompletion of the PDU session establishment procedure. Furthermore, eachapparatus may perform the present procedure multiple times to establishmultiple PDU sessions.

1.3.2.1. Example of PDU Session Establishment Procedure

An example of a process of performing the PDU session establishmentprocedure will be described with reference to FIG. 11. Each step of thepresent procedure will be described below. First, the UE_A 10 transmitsa PDU Session Establishment Request message to the core network_B viathe access network_B (S1100) to initiate the PDU session establishmentprocedure.

Specifically, the UE_A 10 transmits the PDU session establishmentrequest message to the AMF_A 240 in the core network_B 190 via the NRnode_A 122 by way of the N1 interface (S1100). The AMF_A receives thePDU session establishment request message, and performs the thirdcondition determination. The third condition determination is for theAMF_A to determine whether to accept the request of the UE_A 10. In thethird condition determination, the AMF_A determines whether the fifthcondition determination is true or false. The core network_B initiates aprocess #1 in the core network (S1101) in a case that the thirdcondition determination is true, or initiates the procedure (B) in thepresent procedure in a case that the third condition determination isfalse. Note that steps in the case that the third conditiondetermination is false will be described later. Here, the process #1 inthe core network may be SMF selection by the AMF_A in the core network_B190, and/or transmission and/or reception of the PDU sessionestablishment request message between the AMF_A and the SMF_A.

The core network_B 190 starts the process #1 in the core network. In theprocess #1 in the core network, the AMF_A 240 may select the SMF_A 230as the NF to which the PDU session establishment request message isrouted, and transmit or forward the PDU session establishment requestmessage to the selected SMF_A 230 by way of the N11 interface. Here, theAMF_A 240 may select the SMF_A 230 of the routing destination, based onthe information included in the PDU session establishment requestmessage. More specifically, the AMF_A 240 may select the SMF_A 230 ofthe routing destination, based on each piece of identificationinformation acquired based on the reception of the PDU sessionestablishment request message, and/or the subscriber information, and/orthe capability information of the network, and/or the operator policy,and/or the state of the network, and/or the context already held by theAMF_A 240.

The PDU session establishment request message may be a NAS message. ThePDU session establishment request message only needs to be a messagerequesting the PDU session establishment and not limited to this.

Here, the UE_A 10 may include one or more pieces of the firstidentification information to fourth identification information in thePDU session establishment request message, or may include these piecesof identification information to indicate a request of the UE_A 10. Notethat two or more pieces of identification information of these pieces ofidentification information may be configured as one or more pieces ofidentification information.

Moreover, the UE_A 10 may transmit the first identification informationand/or the second identification information and/or the thirdidentification information and/or the fourth identification informationwith being included in the PDU session establishment request message torequest establishment of a PDU session belonging to a network slice,indicate a network slice to which a PDU session requested by the UE_A 10belongs, or indicate a network slice to which a PDU session is going tobelong.

To be more specific, the UE_A 10 may transmit the first identificationinformation and the second identification information with beingassociated with each other to request establishment of a PDU sessionbelonging to a network slice, indicate a network slice to which a PDUsession requested by the UE_A 10 belongs, or indicate a network slice towhich a PDU session is to belong, in a PDU session established for a DNidentified by the second identification information.

Further, the UE_A 10 may transmit two or more pieces of identificationinformation among the first identification information to fourthidentification information with being combined with each other toperform the request combined with the above described matters. Note thatthe matters indicated by the UE_A 10 transmitting the identificationinformation may not be limited to these.

Note that the UE_A 10 may determine which piece of identificationinformation among the first identification information to fourthidentification information is to be included in the PDU sessionestablishment request message, based on the capability information ofthe UE_A 10, and/or a policy such as a UE policy, and/or a preference ofthe UE_A 10, and/or the application (higher layer). Note that thedetermination performed by the UE_A 10 as to which piece ofidentification information is to be included in the PDU sessionestablishment request message is not limited to the determinationdescribed above.

The SMF_A 230 in the core network_B 190 receives the PDU sessionestablishment request message and performs the third conditiondetermination. The third condition determination is for the SMF_A 230 todetermine whether to accept a request of the UE_A 10. In the thirdcondition determination, the SMF_A 230 determines whether the thirdcondition determination is true or false. The SMF_A 230 initiates theprocedure (A) in the present procedure in a case that the thirdcondition determination is true, or initiates the procedure (B) in thepresent procedure in a case that the third condition determination isfalse. Note that steps in the case that the third conditiondetermination is false will be described later.

Hereinafter, steps in the case that third condition determination istrue, that is, the steps in the procedure (A) in the present procedurewill be described. The SMF_A 230 selects the UPF_A 235 in which a PDUsession is established, and performs an eleventh conditiondetermination.

Here, the eleventh condition determination is for each apparatus todetermine whether to perform a process #2 in the core network. Here, theprocess #2 in the core network may include initiating and/or performingof a PDU session establishment authentication procedure by eachapparatus, and/or transmission and/or reception of a SessionEstablishment request message between the SMF_A and UPF_A in the corenetwork_B 190, and/or transmission and/or reception of a SessionEstablishment response message, and the like (S1103). In the eleventhcondition determination, the SMF_A 230 determines whether the eleventhcondition determination is true or false. The SMF_A 230 initiates PDUsession establishment authentication/authorization procedure in a casethat the eleventh condition determination is true, or omits the PDUsession establishment authentication/authorization procedure in a casethat the eleventh condition determination is false. Note that details ofthe PDU session establishment authentication/authorization procedure inthe process #2 in the core network are described later.

Next, the SMF_A 230 transmits a session establishment request message tothe selected UPF_A 235, based on the eleventh condition determinationand/or completion of the PDU session establishmentauthentication/authorization procedure, to initiate the procedure (A) inthe present procedure. Note that, the SMF_A 230 may not initiate theprocedure (A) in the present procedure, based on the completion of thePDU session establishment authentication/authorization procedure, butmay initiate the procedure (B) in the present procedure.

Here, the SMF_A 230 may select one or more UPFs_A 235, based on eachpiece of identification information acquired based on the reception ofthe PDU session establishment request message, and/or the capabilityinformation of the network, and/or the subscriber information, and/orthe operator policy, and/or the state of the network, and/or the contextalready held by the SMF_A 230. Note that in a case that multiple UPFs_A235 are selected, the SMF_A 230 may transmit the session establishmentrequest message to each UPF_A 235.

The UPF_A 235 receives the session establishment request message andcreates a context for the PDU session. In addition, the UPF_A 235transmits the session establishment response message to the SMF_A 230,based on the reception of the session establishment request messageand/or the creation of the context for the PDU session. Furthermore, theSMF_A 230 receives a session establishment response message. Note thatthe session establishment request message and the session establishmentresponse message may be control messages transmitted and/or received onthe N4 interface. Further, the session establishment response messagemay be a response message to the session establishment request message.

Further, the SMF_A 230 may assign an address to be assigned to the UE_A10, based on the reception of the PDU session establishment requestmessage and/or the selection of the UPF_A 235 and/or the reception ofthe session establishment response message. Note that the SMF_A 230 mayassign the address to be assigned to the UE_A 10 during the PDU sessionestablishment procedure, or may assign the address after the completionof the PDU session establishment procedure.

Specifically, in a case that the SMF_A 230 assigns the IPv4 addresswithout using the DHCPv4, the SMF_A 230 may assign the address duringthe PDU session establishment procedure or may transmit the assignedaddress to the UE_A 10. In addition, in a case that the SMF_A 230assigns the IPv4 address, and/or the IPv6 address, and/or the IPv6prefix using the DHCPv4 or the DHCPv6 or Stateless AddressAutoconfiguration (SLAAC), the SMF_A 230 may assign the address afterthe PDU session establishment procedure or may transmit the assignedaddress to the UE_A 10. Note that the address allocation performed bySMF_A 230 is not limited to these.

Furthermore, the SMF_A 230 may transmit the allocated address with beingincluded in the PDU session establishment accept message to the UE_A 10,based on the completion of the address allocation of the address to beallocated to the UE_A 10, or may transmit to the UE_A 10 after thecompletion of the PDU session establishment procedure.

The SMF_A 230 transmits a PDU session establishment accept message tothe UE_A 10 via the AMF_A 240, based on the reception of the PDU sessionestablishment request message, and/or the selection of the UPF_A 235,and/or the reception of the session establishment response message,and/or the completion of the address allocation of the address to beallocated to the UE_A 10 (S1110).

Specifically, the SMF_A 230 transmits the PDU session establishmentaccept message to the AMF_A 240 by way of the N11 interface, and theAMF_A 240 receiving the PDU session establishment accept messagetransmits the PDU session establishment accept message to the UE_A 10 byway of the N1 interface.

Note that in a case that the PDU session is PDN connection, the PDUsession establishment accept message may be a PDN connectivity acceptmessage. Furthermore, the PDU session establishment accept message maybe a NAS message transmitted and/or received on the N11 interface andthe N1 interface. The PDU session establishment accept message is notlimited to the PDU session establishment accept message described above,and only needs to be a message indicating the acceptance of theestablishment of the PDU session.

The UE_A 10 receives the PDU session establishment accept message fromthe SMF_A 230. The UE_A 10 receives the PDU session establishment acceptmessage to recognize the contents of various pieces of identificationinformation included in the PDU session establishment accept message.

Next, the UE_A 10 transmits the PDU session establishment completemessage to the SMF_A 230 via the AMF_A 240, based on completion of thereception of the PDU session establishment accept message (S1114).Furthermore, the SMF_A 230 receives the PDU session establishmentcomplete message, and performs the second condition determination.

Specifically, the UE_A 10 transmits the PDU session establishmentcomplete message to the AMF_A 240 by way of the N1 interface, and theAMF_A 240 receiving the PDU session establishment complete messagetransmits the PDU session establishment complete message to the SMF_A230 by way of the N1 interface.

Note that in a case that the PDU session is PDN connection, the PDUsession establishment complete message may be a PDN Connectivitycomplete message, or may be an Activate default EPS bearer contextaccept message. Furthermore, the PDU session establishment completemessage may be a NAS message transmitted and/or received on the N1interface and the N11 interface. The PDU session establishment completemessage only needs to be a response message to the PDU sessionestablishment accept message. However, the PDU session establishmentcomplete message is not limited to this, and only needs to be a messageindicating that the PDU session establishment procedure is completed.

The second condition determination is for the SMF_A 230 to determine atype of message to be transmitted and/or received on the N4 interface.In a case that the second condition determination is true, a process #3in the core network may be started (S1115). Here, the process #3 in thecore network may include transmission and/or reception of a SessionModification request message and/or transmission and/or reception of aSession Modification response message. The SMF_A 230 transmits thesession modification request message to the UPF_A 235, and furtherreceives the session modification accept message transmitted from theUPF_A 235 that has received the session modification request message. Ina case that the second condition determination is false, the SMF_A 230performs the process #2 in the core network. Specifically, the SMF_Atransmits the session establishment request message to the UPF_A 235,and further receives the session modification accept message transmittedfrom the UPF_A 235 that has received the session establishment requestmessage.

Each apparatus completes the procedure (A) in the present procedure,based on the transmission and/or reception of the PDU sessionestablishment complete message, and/or the transmission and/or receptionof the session modification response message, and/or the transmissionand/or reception of the session establishment response message, and/orthe transmission and/or reception of the Router Advertisement (RA).

Next, steps in the case that the third condition determination is false,that is, the steps in the procedure (B) in the present procedure will bedescribed. The SMF_A 230 transmits a PDU session establishment rejectmessage to the UE_A 10 via the AMF_A 240 (S1122) to initiate theprocedure (B) in the present procedure.

Specifically, the SMF_A 230 transmits the PDU session establishmentreject message to the AMF_A 240 by way of the N11 interface, and theAMF_A 240 receiving the PDU session establishment request messagetransmits the PDU session establishment reject message to the UE_A 10 byway of the N1 interface.

Note that in a case that the PDU session is PDN connection, the PDUsession establishment reject message may be a PDN connectivity rejectmessage. Furthermore, the PDU session establishment reject message maybe a NAS message transmitted and/or received on the N11 interface andthe N1 interface. The PDU session establishment reject message is notlimited to the PDU session establishment reject message described above,and only needs to be a message indicating that the PDU sessionestablishment has been rejected.

Here, the SMF_A 230 may include one or more pieces of identificationinformation among the eleventh identification information to eighteenthidentification information in the PDU session establishment rejectmessage, or may indicate that the request of the UE_A 10 is rejected byincluding these pieces of identification information. Note that two ormore pieces of identification information of these pieces ofidentification information may be configured as one or more pieces ofidentification information.

Moreover, the SMF_A 230 may indicate that a request to establish a PDUsession belonging to a network slice is rejected, or indicate a networkslice to which belonging of a PDU session is not allowed by includingthe eleventh identification information and/or the twelfthidentification information and/or the thirteenth identificationinformation and/or the fourteenth identification information and/or thefifteenth identification information and/or the sixteenth identificationinformation and/or the seventeenth identification information and/or theeighteenth identification information in the PDU session establishmentreject message and transmitting at least one of them.

To be more specific, the SMF_A 230 may transmit the eighteenthidentification information and the twelfth identification informationwith being associated with each other to indicate that a request toestablish a PDU session belonging to a network slice is rejected, orindicate a network slice to which belonging of a PDU session is notallowed, in a PDU session established to a DN identified by the twelfthidentification information.

Further, the SMF_A 230 may transmit the eighteenth identificationinformation with being included in the PDU session establishment rejectmessage to indicate that a request to establish a PDU session belongingto a network slice is rejected, or indicate a network slice to whichbelonging of a PDU session is not allowed, in a registration area and/ortracking area to which the UE_A 10 currently belongs.

Furthermore, the SMF_A 230 may transmit the eighteenth identificationinformation with being included in the PDU session establishment rejectmessage to indicate that a request to establish a PDU session belongingto a network slice is rejected, or indicate a network slice to whichbelonging of a PDU session is not allowed, in an access network to whichthe UE_A 10 currently connects.

Moreover, the SMF_A 230 may transmit the eleventh identificationinformation and/or the fourteenth identification information with beingincluded in the PDU session establishment reject message to indicate avalue of the first timer, or indicate whether the same procedure as thepresent procedure should be performed again after the completion of thepresent procedure.

Furthermore, the SMF_A 230 may transmit two or more pieces ofidentification information among the eleventh identification informationto eighteenth identification information with being combined with eachother to perform the request combined with the above described matters.Note that the matters indicated by the SMF_A 230 transmitting theidentification information may not be limited to these.

Note that the SMF_A 230 may determine which piece of identificationinformation among the eleventh identification information to eighteenthidentification information is to be included in the PDU sessionestablishment reject message, based on the received identificationinformation, and/or the capability information of the network, and/orthe policy such as the operator policy, and/or the state of the network.

Furthermore, the twelfth identification information may be informationindicating the same DNN as the DNN indicated by the secondidentification information. Furthermore, the thirteenth identificationinformation may be information indicating the same PDU session ID as thePDU session ID indicated by the third identification information.Moreover, the eighteenth identification information may be informationtransmitted in a case that the first identification information isreceived and/or in a case that the network slice indicated by the firstidentification information is not allowed by the network. Note thatdetermination performed by the SMF_A 230 as to which piece ofidentification information is to be included in the PDU sessionestablishment reject message is not limited to the determinationdescribed above.

As described above, the core network_B 190 transmits the PDU sessionreject message to notify the UE_A 10 of the congestion control to apply.Note that by doing so, the core network_B 190 may notify of applicationof the congestion control to the UE_A 10, and/or indication to the UE_A10 that the congestion control is to be performed, and/or informationidentifying the type of congestion control to apply, and/or informationidentifying a target of the congestion control, such as DNN and/orS-NSSAI, corresponding to the congestion control to apply, and/or thevalue of the timer associated with the congestion control to apply.

Here, each piece of the above-described information may be informationidentified by one or more pieces of identification information of theeleventh identification information to eighteenth identificationinformation.

The PDU session establishment reject message the UE_A 10 receives fromthe SMF_A 230 may include one or more pieces of identificationinformation among the eleventh identification information to eighteenthidentification information.

Next, the UE_A 10 performs the fourth process, based on the reception ofthe PDU session establishment reject message (S1124). The UE_A 10 mayperform the fourth process, based on the completion of the presentprocedure.

A first example of the fourth process will be described below.

Here, the fourth process may be a process in which the UE_A 10recognizes the matter indicated by the SMF_A 230. The fourth process maybe a process in which the UE_A 10 stores the received identificationinformation as a context, or may be a process in which the UE_A 10forwards the received identification information to the higher layerand/or the lower layer. The fourth process may be a process in which theUE_A 10 recognizes that the request for the present procedure isrejected.

Moreover, in a case that the UE_A 10 receives the fourteenthidentification information and the eleventh identification information,the fourth process may be a process in which the UE_A 10 configures avalue indicated by the fourteenth identification information as thefirst timer value, or a process in which the UE_A 10 starts the firsttimer configured with the timer value. Furthermore, in the case that theUE_A 10 receives the eleventh identification information, the fourthprocess may be a process to perform one or more behaviors of the firstto eleventh behaviors.

Further, in a case that the UE_A 10 receives the eighteenthidentification information and the eleventh identification information,the fourth process may be a process in which the UE_A 10 performs thetwelfth behavior, based on the information identifying the NW sliceincluded in the eighteenth identification and the network sliceassociation rule included in the eighteenth identification informationor the network slice association rule held in advance and configured bythe UE_A 10.

Furthermore, in a case that the UE_A 10 receives the multiple pieces ofthe fourteenth identification information and the eleventhidentification information, the fourth process may be a process in whichthe UE_A 10 performs the thirteenth behavior, based on the multiplefirst timers included in the respective pieces of the fourteenthidentification information and the back-off timer priority managementrule held by the UE_A 10.

Furthermore, in a case that the UE_A 10 receives the multiple pieces ofthe fourteenth identification information and the eleventhidentification information, the fourth process may be a process in whichthe UE_A 10 performs the fourteenth behavior, based on the multiplefirst timers included in the respective pieces of the fourteenthidentification information.

Here, the twelfth to fifteenth behaviors may be the congestion controlsinitiated by the UE_A 10, based on rules and/or policies in the UE_A 10.Specifically, for example, the UE_A 10 may include, in a storage unit/ora controller within the UE_A 10, a policy (UE policy) and/or a rule, amanagement function of a policy and/or a rule, a policy enforcer causingthe UE_A 10 to operate based on a policy and/or a rule, one or multipleapplications, and a session management instance (session manager) formanaging one or multiple PDU sessions to establish or attempt toestablish based on a request from each application, and may perform,based on these, any of the twelfth to fifteenth behaviors as the fourthprocess to implement the congestion control initiated by the UE_A 10.Here, the policy and/or the rule may include any one or multiple of thenetwork slice association rule and/or the back-off timer prioritymanagement rule and/or the Network Slice Selection Policy (NSSP), whichfurthermore may be preconfigured for the UE_A 10, or may be receivedfrom the network. Here, the policy enforcer may be an NSSP enforcer.Here, the application may be a protocol of the application layer, andthe PDU session may be established or attempted to be established basedon a request from the protocol of the application layer. Here, thesession management instance may be a dynamically generated softwareelement in a PDU session unit. Here, as internal processing in the UE_A10, the S-NSSAI may be grouped or a process based on the grouping of theS-NSSAI may be performed. Note that the internal configuration andprocessing in the UE_A 10 may not be limited thereto, and each elementmay be implemented in software or may be performed as softwareprocessing in the UE_A 10.

Furthermore, the UE_A 10 may switch to the EPS, in the fourth process orbased on the completion of the fourth process, and may start theposition registration at the EPS, based on the DCN ID included in theeighteenth identification information. Note that the switch to the EPSby the UE_A 10 may be performed based on the handover procedure, or maybe a RAT switch initiated by the UE_A 10. Additionally, in a case thatthe UE_A 10 receives the eighteenth identification information includingthe DCN ID, the UE_A 10 may perform the switch to the EPS during thefourth process or after the completion of the fourth process.

Furthermore, the fourth process may be a process in which the UE_A 10initiates again the present procedure after a certain time periodelapses, or a process in which the UE_A 10 transitions to a state wherethe request of the UE_A 10 is limited or restricted.

Note that the UE_A 10 may transition to the first state in accordancewith the completion of the fourth process.

Next, a second example of the fourth process will be described.

Here, the fourth process may be a process in which the UE_A 10recognizes the matter indicated by the SMF_A 230. The fourth process maybe a process in which the UE_A 10 stores the received identificationinformation as a context, or may be a process in which the UE_A 10forwards the received identification information to the higher layerand/or the lower layer.

Furthermore, in the fourth process, a process may be performed ofidentifying that the congestion control is applied, based on one or morepieces of identification information among the eleventh identificationinformation to eighteenth identification information.

Furthermore, in the fourth process, a process may be performed ofidentifying which type of congestion control is applied among the firstto fourth congestion controls, and a process may be performed ofidentifying the DNN and/or the S-NSSAI associated with the congestioncontrol to apply, based on one or more pieces of identificationinformation among the eleventh identification information to eighteenthidentification information. More specifically, the present process maybe a process described in the fifteenth behavior.

Furthermore, in the fourth process, the UE may identify or configure avalue configured for the first timer indicated by the fourteenthidentification information associated with the congestion control toapply, based on one or more pieces of identification information amongthe eleventh identification information to eighteenth identificationinformation, and the UE may start to count the first timer with thevalue. To be more specific, the present process may be a processdescribed in the eighth behavior.

Furthermore, in the fourth process, one or more of the first to seventhbehaviors may be performed in accordance with the start or completion ofany of the processes described above.

Furthermore, in the fourth process, one or more of the ninth tofifteenth behaviors may be performed in accordance with the start orcompletion of any of the processes described above.

Note that the UE_A 10 may transition to the first state in accordancewith the completion of the fourth process.

Hereinbefore, the processing contents are described for the fourthprocess by using the first example and the second example, but thefourth process may not be limited to these processes. For example, thefourth process can be a combination of a portion of the multipledetailed processes described in the first example and a portion of themultiple detailed processes described in the second example.

Further, the UE_A 10 may receive the PDU session establishment rejectmessage, or not receive the PDU session establishment accept message,and thereby, recognize that the request of the UE_A 10 is rejected. Eachapparatus completes the procedure (B) in the present procedure, based onthe transmission and/or reception of the PDU session establishmentreject message.

Each apparatus completes the present procedure, based on completion ofthe procedure (A) or (B) in the present procedure. Note that eachapparatus may transition to a state in which the PDU session isestablished, based on the completion of the procedure (A) in the presentprocedure, or each apparatus may recognize that the present procedure isrejected, may transition to a state in which the PDU session is notestablished, or may transition to the first state, based on thecompletion of the procedure (B) in the present procedure.

Furthermore, each apparatus may perform processing, based onidentification information transmitted and/or received in the presentprocedure, based on completion of the present procedure. In other words,the UE_A 10 may perform the fourth process, based on the completion ofthe present procedure, or transition to the first state after thecompletion of the fourth process.

The third condition determination may be performed based on theidentification information included in the PDU session establishmentrequest message, and/or the subscriber information, and/or the operatorpolicy. For example, the third condition determination may be true in acase that the network allows the request of the UE_A 10. The thirdcondition determination may be false in a case that the network does notallow the request of the UE_A 10. The third condition determination maybe true in a case that a network to which the UE_A 10 is connectedand/or the device within the network support the function the UE_A 10requests, or may be false in a case of not supporting the function. Thethird condition determination may be true in a case that the network isdetermined to be in a congested state, or may be false in a casedetermined to not be in a congested state. Note that conditions withwhich true or false of the third condition determination is determinedmay not be limited to the previously described conditions.

The second condition determination may be performed based on whether thesession on the N4 interface for the PDU session has been established.For example, in a case that the session on the N4 interface for the PDUsession has been established, the second condition determination may betrue, and in a case that the session on the N4 interface for the PDUsession is not established, the second condition determination may befalse. Conditions for determining true or false of the second conditiondetermination need not be limited to the above-described conditions.

The eleventh condition determination may be performed based on theidentification information included in the PDU session establishmentrequest message, and/or the subscriber information, and/or the operatorpolicy. For example, the eleventh condition determination may be true ina case that the network allows the authentication and/or authorizationby the DN_A 5 to be performed during the present procedure. The eleventhcondition determination may be false in a case that the network does notallow the authentication and/or authorization by the DN_A 5 to beperformed during the present procedure. The eleventh conditiondetermination may be true in a case that a network to which the UE_A 10is connected and/or the device within the network support the performingof the authentication and/or authorization by the DN_A 5 during thepresent procedure, or may be false in a case of not supporting. Theeleventh condition determination may be true in a case that the 61stidentification information is received, or may be false in a case of notreceived. In other words, the eleventh condition determination may betrue in a case that information such as SM PDU DN Request Containerand/or a container containing multiple pieces of information arereceived, and may be false in a case of not received. Note thatconditions with which true or false of the eleventh conditiondetermination is determined may not be limited to the previouslydescribed conditions.

The transmission and/or reception of the PDU session reject message inthe above-described procedure causes the core network_B 190 to notifythe UE_A 10 of the congestion control to apply, and the UE_A 10 canapply the congestion control indicated by the core network_B 190. Notethat the core network_B 190 and the UE_A 10 may apply multiplecongestion controls by performing the procedures and processes describedin the present procedure multiple times. Note that each congestioncontrol to apply may be a different type of congestion control, and/or acongestion control corresponding to a different DNN, and/or a congestioncontrol corresponding to a different S-NSSAI, and/or a congestioncontrol different in a combination of the DNN and the S-NSSAI.

1.3.3. Overview of Network-Initiated Session Management Procedure

Next, an overview of the network-initiated session management procedurewill be described. Hereinafter, the network-initiated session managementprocedure is also referred to as the present procedure. The procedure isa procedure for a session management initiated by the network andperformed for the established PDU session. Note that the presentprocedure may be performed at any timing after the registrationprocedure and/or the PDU session establishment procedure described aboveare completed and each apparatus transitions to the first state. Eachapparatus may transmit and/or receive a message including identificationinformation for stopping or changing the congestion control during theprocedure, or may start a behavior based on a new congestion controlindicated by the network based on the completion of the presentprocedure.

Alternatively, the UE_A 10 may stop the application of the congestioncontrol identified based on the control information transmitted and/orreceived by the present procedure. In other words, the core network_B190 can initiate the present procedure and further transmit a controlmessage and control information of the present procedure to the UE_A 10to notify the UE_A 10 to stop the application of the congestion controlthat can be identified using the control information.

Note that the present procedure may be a network-initiated PDU sessionmodification procedure, and/or a network-initiated PDU session releaseprocedure, or the like, or, without limitation, may be anetwork-initiated session management procedure. Note that each apparatusmay transmit and/or receive a PDU session modification message in thenetwork-initiated PDU session modification procedure, or may transmitand/or receive a PDU session release message in the network-initiatedPDU session release procedure.

1.3.3.1. First Example of Network-Initiated Session Management Procedure

An example of the network-initiated session management procedure will bedescribed using FIG. 12. In this section, the present procedure refersto the network-initiated session management procedure. Each step of thepresent procedure will be described below.

As described above, based on the completion of the registrationprocedure and/or the PDU session establishment procedure, each apparatusin the UE_A 10 and core network_B 190 transitioning to the first state(S1200) initiates a network-initiated session management procedure atany timing. Here, the apparatus initiating the present procedure in thecore network_B 190 may be the SMF_A and/or the AMF_A, and the UE_A maytransmit and/or receive a message in the present procedure via the AMF_Aand/or the access network_B.

Specifically, the apparatus in the core network_B 190 transmits anetwork-initiated session management request message to the UE_A(S1202). Here, the apparatus in the core network_B 190 may include the21st identification information in the network-initiated sessionmanagement request message, or may indicate that the request of the corenetwork_B 190 by including the identification information.

Next, the UE_A receiving the network-initiated session managementrequest message transmits a network-initiated session managementcomplete message (S1204). Furthermore, the UE_A may perform the fifthprocess, based on the 21st identification information received from thecore network_B 190 (S1206), and complete the present procedure. The UE_A10 may perform the fifth process, based on the completion of the presentprocedure.

An example of the fifth process will be described below.

Here, the fifth process may be a process in which the UE_A 10 recognizesthe matter indicated by the core network_B 190, or may be a process inwhich the UE_A 10 recognizes the request of the core network_B 190. Thefifth process may be a process in which the UE_A 10 stores the receivedidentification information as a context, or may be a process in whichthe UE_A 10 forwards the received identification information to thehigher layer and/or the lower layer.

A message transmitted and/or received in the network-initiated sessionmanagement request may be a PDU session modification command (PDUSESSION MODIFICATION COMMAND), or a PDU session release command (PDUSESSION RELEASE COMMAND) without limitation.

Note that the UE_A 10 may perform the congestion control identificationprocess applied by the UE_A 10 in the fifth process, based on thereceived 21st identification information. Here, the congestion controlidentification process may be the seventeenth behavior.

Moreover, in the case that the UE_A 10 receives the 21st identificationinformation, the fifth process may be the sixteenth behavior.Specifically, for example, the process may be a process to stop one ormultiple timers performed, based on the fourth process described above.

In other words, the UE_A 10 in a case of receiving the 21stidentification information performs the seventeenth behavior to identifythe congestion control that is to be stopped or changed indicated by thenetwork, and then, performs the sixteenth behavior to stop or change theidentified congestion control.

Furthermore, each apparatus may perform processing, based onidentification information transmitted and/or received in the presentprocedure, based on completion of the present procedure. In other words,the UE_A 10 may perform the fifth process, based on the completion ofthe present procedure, or perform the present procedure after thecompletion of the fifth process.

In the above-described procedure, through the transmission and/orreception of the network-initiated session management request message,the core network_B 190 can indicate to the UE_A 10 that the congestioncontrol the UE_A 10 already applies is to be stopped or changed.Furthermore, the UE_A 10 may stop or change the congestion control theUE_A 10 applies, based on the network-initiated session managementrequest message. Here, in a case that the UE_A 10 applies one or morecongestion controls, the UE_A 10 may identify the congestion control tobe stopped or changed, based on the reception of the identificationinformation included in the network-initiated session management requestmessage from the core network_B 190. Note that each congestion controlto apply may be a different type of congestion control, and/or acongestion control corresponding to a different DNN, and/or a congestioncontrol corresponding to a different S-NSSAI, and/or a congestioncontrol different in a combination of the DNN and the S-NSSAI.

1.3.3.2. Second Example of Network-Initiated Session ManagementProcedure

The first example of the network-initiated session management proceduredescribed in the section 1.3.3.1 describes the example in which thecongestion control is stopped during the procedure, regardless of whichcongestion control of the first to fourth congestion controls thecongestion control applied to the UE_A 10 is.

The procedure described in the first example of the network-initiatedsession management procedure described in section 1.3.3.1 is not limitedto the above example and may be a procedure performed in accordance withthe congestion control. For example, the procedure may be performed forthe congestion controls categorized into the first congestion control,the third congestion control, and the fourth congestion control, amongone or multiple congestion controls the UE_A 10 applies.

In other words, the UE_A 10 may stop the congestion controlscorresponding to the first congestion control, the third congestioncontrol, and the fourth congestion control by the fifth process.

In a case that the UE_10 receives a network-initiated session managementrequest message for the second congestion control while the count of theback-off timer associated with the second congestion control is running,the UE_A 10 may respond to the core network_B 190 without stopping theback-off timer associated with the second congestion control.

In other words, in a case that the UE_A 10, while the count of theback-off timer associated with the S-NSSAI #A is running, receives thenetwork-initiated session management request message for the congestedS-NSSAI #A and any DNN, the UE_A 10 may respond to the core network_B190 without stopping the back-off timer associated with the S-NSSAI #A.

In this manner, for the second congestion control, the UE_A 10, inreceiving the network-initiated session management request message, maytransmit the response message for the network-initiated sessionmanagement request message to the core network_B 190, but may continuethe congestion control. Accordingly, the UE-initiated session managementrequest message transmission regulated by the second congestion controlmay continue to be prohibited.

Here, as described above, the network-initiated session managementrequest message in the present embodiment may be a PDU sessionmodification command (PDU SESSION MODIFICATION COMMAND) message in thenetwork-initiated PDU session modification procedure, or a PDU sessionrelease command (PDU SESSION RELEASE COMMAND) message in thenetwork-initiated PDU session release procedure.

Moreover, as described above, the network-initiated session managementcomplete message responsive to the PDU session modification commandmessage in the present embodiment may be a PDU session modificationcomplete message (PDU SESSION MODIFICATION COMPLETE), and thenetwork-initiated session management complete message responsive to thePDU session release command message in the present embodiment may be aPDU session release complete message (PDU SESSION RELEASE COMPLETE). Ina case that the network-initiated session management request message isa PDU session modification command and/or a PDU session release message,the UE_A 10 and the core network_B 190 may be configured to perform thefurther detailed processes described below in addition to theabove-described processes.

For example, in a case that the core network_B 190 transmits thenetwork-initiated session management request message includinginformation indicating a reactivation request (Reactivation Required),the core network_B 190 may perform the process as follows. Note that theinformation indicating the reactivation request (Reactivation Required)is information indicating that activation is requested, and specificexamples may include the 5G session management cause value #39 (5GSMCause #39).

Hereinafter, the first process and procedure example in a case ofreceiving information indicating the reactivation request will bedescribed.

In a case that the UE_A 10 receives a network-initiated sessionmanagement request message including information indicating areactivation request (Reactivation Required), the UE_A 10 does not againinitiate the UE-initiated PDU session establishment procedureimmediately after the completion of the network-initiated sessionmanagement procedure but waits for the congestion control to be releasedto again initiate the UE-initiated PDU session establishment procedure.Here, the UE-initiated PDU session establishment procedure may be aUE-initiated PDU session establishment procedure for the PDU sessiontype provided in the UE-initiated PDU establishment procedure in a casethat the PDU session to be changed or released is established, the SSCmode, and the DNN and the S-NSSAI.

Note that waiting for the congestion control to be released may beperformance after the timer associated with the second congestioncontrol Expires. In other words, waiting for the congestion control tobe released may be the performing after the completion of counting ofthe timer associated with the second congestion control and/or after thetimer value associated with the second congestion control becomes zero.

Furthermore, the UE_A 10 may include the following supplementalinformation in the network-initiated session management completemessage.

The supplemental information may be information indicating that thetimer is waited for to be expired and/or information indicating aremaining timer value. Here, the timer may be a timer associated withthe second congestion control. The timer being waited for to be expiredmay be performance after the timer Expires. In other words, waiting forthe congestion control to be released may be the performing after thecompletion of counting of the timer associated with the secondcongestion control and/or after the timer value associated with thesecond congestion control becomes zero.

Note that the core network_B 190 may receive the network-initiatedsession management complete message including the supplementalinformation and recognize the remaining timer value. Furthermore, thecore network_B 190 may recognize that the UE-initiated PDU sessionestablishment procedure is initiated after the time of the valueindicated by the remaining timer elapses.

Here, the remaining timer recognized by the core network_B 190 may be avalue indicated by the received supplemental information, or a valuetaking account of an offset between a transmission time of the UE_A 10and a reception time by the core network_B 190 of the network-initiatedsession management complete message with respect to the value indicatedby the received supplemental information.

In addition, not only the first process and procedure example in a caseof receiving the information indicating the reactivation request butalso the second process and procedure example in a case of receiving theinformation indicating the reactivation request as described below maybe performed.

As described above, for the second congestion control, the UE_A 10, inreceiving the network-initiated session management request message, maytransmit the response message for the network-initiated sessionmanagement request message to the core network_B 190, but may continuethe congestion control. Thus, although the UE-initiated sessionmanagement request message transmission regulated by the secondcongestion control continues to be suppressed, the UE_A 10 and/or thecore network_B 190 may be configured to be only allowed to againinitiate the UE-initiated PDU session establishment procedure.

In other words, in the case that the UE_A 10 receives anetwork-initiated session management request message includinginformation indicating a reactivation request (Reactivation Required),the UE_A 10 again initiates the UE-initiated PDU session establishmentprocedure after the completion of the network-initiatednetwork-initiated session management procedure. Here, the UE-initiatedPDU session establishment procedure may be a UE-initiated PDU sessionestablishment procedure for the PDU session type provided in theUE-initiated PDU establishment procedure in a case that the PDU sessionto be changed or released is established, the SSC mode, and the DNN andthe S-NSSAI.

Note that while the UE_A 10 continues the application of congestioncontrol, the UE_A 10 and the core network_B 190 may perform and completeprocedures allowed as an exception but the UE_A 10 may be prohibitedfrom initiating other UE-initiated session management proceduresprohibited by the second congestion control.

In addition, not only the first and second processes and procedureexamples in a case of receiving the information indicating thereactivation request but also the third process and procedure example ina case of receiving the information indicating the reactivation requestmay be performed.

As described above, for the second congestion control, the UE_A 10, inreceiving the network-initiated session management request message,transmits the response message for the network-initiated sessionmanagement request message to the core network_B 190. Furthermore, inthe case that the UE_A 10 receives the network-initiated sessionmanagement request message including information indicating thereactivation request (Reactivation Required), the UE_A 10 may stop theapplication of the second congestion control.

In other words, the UE_A 10 may continue the congestion control in acase that the network-initiated session management request message doesnot include information indicating the reactivation request(Reactivation Required). In this case, the UE-initiated sessionmanagement request message transmission regulated by the secondcongestion control may continue to be prohibited.

Accordingly, in the case that the UE_A 10 receives a network-initiatedsession management request message including information indicating areactivation request (Reactivation Required), the UE_A 10 againinitiates the UE-initiated PDU session establishment procedure after thecompletion of the network-initiated network-initiated session managementprocedure. Here, the UE-initiated PDU session establishment proceduremay be a UE-initiated PDU session establishment procedure for the PDUsession type provided in the UE-initiated PDU establishment procedure ina case that the PDU session to be changed or released is established,the SSC mode, and the DNN and the S-NSSAI.

In addition, without limitation on the first, second, and thirdprocesses and procedure examples in a case of receiving the informationindicating the reactivation request, the information indicating thereactivation request may be configured to be not transmitted by the corenetwork_B 190.

To be more specific, the core network_B 190, in the case of transmittingthe network-initiated session management request message to the UE_A 10applying the congestion control, may be configured to prohibit theinformation indicating a reactivation request (Reactivation Required)from being included.

Alternatively, the core network_B 190, in the case of transmitting thenetwork-initiated session management request message to the UE_A 10applying the second congestion control, may be configured to prohibitthe information indicating a reactivation request (ReactivationRequired) from being included.

Hereinbefore, the processes and procedures of the UE_A 10 and the corenetwork_B 190 are described. The process of the core network_B 190described in this section may be, more specifically, a process performedby a control apparatus such as the SMF_A 230 and/or the AMF_A 240 whichare the apparatuses in the core network_B 190. Therefore, the corenetwork_B 190 transmitting and/or receiving the control message mayrefer to the control apparatus such as the SMF_A 230 and/or the AMF_A240, which are the apparatuses in the core network_B 190, transmittingand/or receiving the control message.

Furthermore, not limited to this section, in the expression used in thedescription of the present embodiment, releasing the congestion controlor stopping the congestion control may include a process of stopping theback-off timer associated with the congestion control, and continuingapplication for the congestion control or continuing the congestioncontrol may include continuing to count the back-off timer associatedwith congestion control.

Also, in the first, second, and third processes and procedure examplesin a case of receiving the information indicating the reactivationrequest described in this section, the network-initiated sessionmanagement request message and/or the network-initiated sessionmanagement procedure are described as those for the congested S-NSSAI #Aand any DNN with respect to the UE_A 10.

In other words, the congested S-NSSAI #A and any DNN may be the S-NSSAI#A and any DNN associated with the PDU session subjected to thenetwork-initiated session management request message and/or thenetwork-initiated session management procedure.

Note that the UE_A 10 and the core network_B 190 may perform an anchorrelocation procedure in the SSC mode 2 including the procedure in thissection, and switch to an anchor of the PDU session or to a PDU sessiondifferent in the anchor to continue the communication. Here, the anchorrelocation procedure in the SSC mode 2 is a procedure initiated by thecore network_B 190, and the procedure involved in the transmission ofthe PDU session release command performed in this procedure may be anyprocedure described in this section.

The UE_A 10 and the core network_B 190 may perform an anchor relocationprocedure in the SSC mode 3 including the procedure in this section, andswitch to an anchor of the PDU session or to a PDU session different inthe anchor to continue the communication. Here, the anchor relocationprocedure in the SSC mode 3 is a procedure initiated by the corenetwork_B 190, and the procedure involved in the transmission of the PDUsession modification command performed in this procedure may be anyprocedure described in this section.

Next, in a state where the congestion control is applied, a process in acase that the UE moves with PLMN change will be described.

Here, a process in a case that the UE_A 10 changes the PLMN in a statewhere particularly the first congestion control is applied will bedescribed. Here, the first congestion control and the process regulatedin a case that the first congestion control is applied may be asdescribed above.

Again, the first congestion control may be a DNN based congestioncontrol. For example, the first congestion control may be a congestioncontrol the NW applies to the UE_A 10, based on a message rejecting aUE-initiated session management request in a case that the NW receivesthe UE-initiated session management request using the DNN #A from theUE_A 10 and convergence to a specific DNN, e.g., the DNN #A is detectedat the NW. In this case, in the application of the first congestioncontrol, the UE_A 10 may be configured to start counting the back-offtimer corresponding to the first congestion control received from the NWand to not transmit the UE-initiated session management request usingthe DNN #A until the back-off timer expires. Note that using the DNN maybe to include the DNN information in the UE-initiated session managementrequest such as a PDU session establishment request message.

Here, for the convenience of description, such first congestion controlis represented as a “first congestion control for the specific DNN”.

In the first congestion control, even in a case that the UE-initiatedsession management request does not include the DNN information, the NWmay select a default DNN as a congestion control target on theinitiative of the NW. In other words, the first congestion control maybe a congestion control the NW applies to the UE_A 10, based on amessage rejecting a UE-initiated session management request in a casethat the NW receives the UE-initiated session management request notusing the DNN information from the UE_A 10 and convergence to a defaultDNN is detected at the NW. In this case, in the application of the firstcongestion control, the UE_A 10 may be configured to start counting theback-off timer corresponding to the first congestion control receivedfrom the NW and to not transmit the UE-initiated session managementrequest not using the DNN until the back-off timer expires. Note thatnot using the DNN may be not including the DNN information in theUE-initiated session management request such as a PDU sessionestablishment request message.

Here, for the convenience of description, such first congestion controlfor the default DNN is applied based on the UE-initiated sessionmanagement request not using the DNN information, and thus isrepresented as a “congestion control for No DNN” to distinguish from thefirst congestion control for the specific DNN. Furthermore, theUE-initiated session management request such as a PDU sessionestablishment request message not using the DNN is represented as aUE-initiated session management request using No DNN. For example, thePDU session establishment request message using No DNN is a PDU sessionestablishment request message not using the DNN.

The UE_A 10 may be so configured, in a case that the UE_A 10, inchanging the PLMN, is counting the back-off timer associated with thefirst congestion control for the specific DNN, or the back-off timerassociated with the first congestion control for the specific DNN isdeactivated, that the UE_A 10 can transmit a PDU session establishmentrequest message by using this specific DNN in the new PLMN. Accordingly,based on this configuration, the UE_10 may transmit a PDU sessionestablishment request message using this specific DNN.

Here, the UE_A 10 may continue the counting until the timer expireswithout stopping the counted back-off timer. Alternatively, the UE_A 10may continue to hold the deactivated back-off timer in a state of beingdeactivated.

In this manner, the first congestion control for the specific DNN may beassociated with the PLMN.

For example, in a case that the first congestion control for thespecific DNN is applied, the UE associates the back-off timer with thePLMN and the specific DNN to start counting, or in a case that theback-off timer is not zero or deactivated, the UE does not perform thePDU session establishment using the specific DNN associated with theback-off timer in the PLMN associated with the back-off timer. Inaddition, in a case that the back-off timer is deactivated, the UE doesnot perform the PDU session establishment using the specific DNNassociated with the back-off timer in the PLMN associated with theback-off timer until the terminal is turned OFF or the USIM isretrieved. In the case that the back-off timer is zero, the UE mayperform the PDU session establishment using the specific DNN associatedwith the back-off timer in the PLMN associated with the back-off timer.

In other words, the UE_A 10 may be so configured, in a case that theUE_A 10, in changing the PLMN, is counting the back-off timer associatedwith the first congestion control for the specific DNN and the PLMNbefore changed, or in a case that the back-off timer associated with thefirst congestion control for the specific DNN and the PLMN beforechanged is deactivated, and further in a case that the UE_A 10 is notcounting the back-off timer associated with the first congestion controlfor the specific DNN and the PLMN after changed, and the back-off timerassociated with the first congestion control for the specific DNN andthe PLMN after changed is not deactivated, that the UE_A 10 can transmita PDU session establishment request message using this specific DNN inthe new PLMN. Furthermore, based on this configuration, the UE_10 maytransmit a PDU session establishment request message using this specificDNN.

The UE_A 10 may be so configured, in a case that the UE_A 10, inchanging the PLMN, is counting the back-off timer associated with thefirst congestion control for No DNN, or the back-off timer associatedwith the first congestion control for No DNN is deactivated, that theUE_A 10 can transmit a PDU session establishment request message notusing the DNN in the new PLMN. Accordingly, based on this configuration,the UE_10 may transmit a PDU session establishment request message usingthis specific DNN.

Here, the UE_A 10 may continue the counting until the timer expireswithout stopping the counted back-off timer. Alternatively, the UE_A 10may continue to hold the deactivated back-off timer in a state of beingdeactivated.

In this manner, the first congestion control for No DNN may beassociated with the PLMN. In other words, the UE_A 10 may be soconfigured, in a case that the UE_A 10, in changing the PLMN, iscounting the back-off timer for the first congestion control for No DNNassociated with the PLMN before changed, or in a case that the back-offtimer for the first congestion control for No DNN associated with thePLMN before changed is deactivated, and further in a case that the UE_A10 is not counting the back-off timer for the first congestion controlfor No DNN associated with the PLMN after changed, and the back-offtimer for the first congestion control for No DNN associated with thePLMN is not deactivated, that the UE_A 10 can transmit a PDU sessionestablishment request message not using the DNN in the new PLMN.Furthermore, based on this configuration, the UE_10 may transmit a PDUsession establishment request message not using the DNN.

As described above, the UE_A 10 may perform the similar processregardless of whether the first congestion control is for the specificDNN or No DNN.

Specifically, the UE_A 10 may be so configured, in a case that the UE_A10, in changing the PLMN, is counting the back-off timer for the firstcongestion control associated with the PLMN before changed, or in a casethat the back-off timer for the first congestion control associated withthe PLMN before changed is deactivated, and further in a case that theUE_A 10 is not counting the back-off timer for the first congestioncontrol associated with the PLMN after changed, and the back-off timerfor the first congestion control associated with the PLMN after changedis not deactivated, that the UE_A 10 can transmit a PDU sessionestablishment request message using the specific DNN and/or a PDUsession establishment request message not using the DNN regulated by thecongestion control associated with the PLMN before changed, in the newPLMN.

Alternatively, the UE_A 10 may perform different processes depending onwhether the first congestion control is for the specific DNN or for NoDNN.

The UE_A 10 may be so configured, in a case that the UE_A 10, inchanging the PLMN, is counting the back-off timer associated with thefirst congestion control for the specific DNN, or the back-off timerassociated with the first congestion control for the specific DNN isdeactivated, that the UE_A 10 does not transmit a PDU sessionestablishment request message using this specific DNN in the new PLMN.Accordingly, based on this configuration, the UE_10 may be regulatedregarding the transmission of a PDU session establishment requestmessage using this specific DNN.

Here, the UE_A 10 may continue the counting until the timer expireswithout stopping the counted back-off timer. Alternatively, the UE_A 10may continue to hold the deactivated back-off timer in a state of beingdeactivated.

In this manner, the first congestion control for the specific DNN may beapplied also in the different PLMN.

On the other hand, the UE_A 10 may be so configured, in a case that theUE_A 10, in changing the PLMN, is counting the back-off timer associatedwith the first congestion control for No DNN, or the back-off timerassociated with the first congestion control for No DNN is deactivated,that the UE_A 10 can transmit a PDU session establishment requestmessage not using the DNN in the new PLMN. Accordingly, based on thisconfiguration, the UE_10 may transmit a PDU session establishmentrequest message using this specific DNN.

Here, the UE_A 10 may continue the counting until the timer expireswithout stopping the counted back-off timer. Alternatively, the UE_A 10may continue to hold the deactivated back-off timer in a state of beingdeactivated.

In this manner, the first congestion control for No DNN may beassociated with the PLMN.

For example, in a case that the first congestion control for No DNN isapplied, the UE associates the back-off timer with the PLMN and No DNNto start counting, or in a case that the back-off timer is not zero ordeactivated, the UE does not perform the PDU session establishment usingNo DNN associated with the back-off timer in the PLMN associated withthe back-off timer. In addition, in a case that the back-off timer isdeactivated, the UE does not perform the PDU session establishment usingNo DNN associated with the back-off timer in the PLMN associated withthe back-off timer until the terminal is turned OFF or the USIM isretrieved. In the case that the back-off timer is zero, the UE mayperform the PDU session establishment using No DNN associated with theback-off timer in the PLMN associated with the back-off timer.

In other words, the UE_A 10 may be so configured, in a case that theUE_A 10, in changing the PLMN, is counting the back-off timer for thefirst congestion control for No DNN associated with the PLMN beforechanged, or in a case that the back-off timer for the first congestioncontrol for No DNN associated with the PLMN before changed isdeactivated, and further in a case that the UE_A 10 is not counting theback-off timer for the first congestion control for No DNN associatedwith the PLMN after changed, and the back-off timer for the firstcongestion control for No DNN associated with the PLMN is notdeactivated, that the UE_A 10 can transmit a PDU session establishmentrequest message not using the DNN in the new PLMN. Furthermore, based onthis configuration, the UE_10 may transmit a PDU session establishmentrequest message not using the DNN.

Here, as the process with the change of the PLMN described above,whether the similar process is performed regardless of whether the firstcongestion control is for the specific DNN or No DNN, or the differentprocess is performed may be configured in advance based on theinformation configured for the UE_A 10, or may be determined dependingon whether or not the second PLMN after changed is the equivalent PLMNfor the first PLMN before changed. For example, in a case that thesecond PLMN after changed is not the equivalent PLMN for the first PLMNbefore changed, the similar process may be applied. In a case that thesecond PLMN after changed is the equivalent PLMN for the first PLMNbefore changed, the different process may be applied.

Furthermore, the UE_A 10 may determine the behavior, based on additionaldetailed conditions, as well as whether or not the second PLMN afterchanged is the equivalent PLMN. For example, the UE_A 10 may beconfigured to perform behaviors different between a case that the secondPLMN after changed is the equivalent PLMN for the first PLMN beforechanged and the registration area is not changed in changing the PLMN,and a case that the second PLMN after changed is the equivalent PLMN forthe first PLMN before changed and the registration area change isinvolved in changing the PLMN.

Note that the behavior of the UE_A 10 performed in each case may be oneof the behaviors in a case that the PLMN is changed described above.

For example, a first example will be described of the case that thesecond PLMN after changed is the equivalent PLMN for the first PLMNbefore changed and the registration area is not changed in changing thePLMN. The UE_A 10 may be so configured, in a case that the UE_A 10, inchanging the PLMN like this, is counting the back-off timer associatedwith the first congestion control for the specific DNN, or the back-offtimer associated with the first congestion control for the specific DNNis deactivated, that the UE_A 10 does not transmit a PDU sessionestablishment request message using this specific DNN in the new PLMN.Accordingly, based on this configuration, the UE_10 may be regulatedregarding the transmission of a PDU session establishment requestmessage using this specific DNN.

A second example will be described of the case that the second PLMNafter changed is the equivalent PLMN for the first PLMN before changedand the registration area is not changed in changing the PLMN. The UE_A10 may be so configured, in a case that the UE_A 10, in changing thePLMN like this, is counting the back-off timer associated with the firstcongestion control for No DNN, or the back-off timer associated with thefirst congestion control for No DNN is deactivated, that the UE_A 10does not transmit a PDU session establishment request message not usingthe DNN in the new PLMN. Accordingly, based on this configuration, theUE_10 may be regulated regarding the transmission of a PDU sessionestablishment request message not using the DNN.

Next, a first example will be described of the case that the second PLMNafter changed is the equivalent PLMN for the first PLMN before changedand the registration area change is involved in changing the PLMN. TheUE_A 10 may be so configured, in a case that the UE_A 10, in changingthe PLMN like this, is counting the back-off timer for the firstcongestion control for No DNN associated with the PLMN before changed,or in a case that the back-off timer for the first congestion controlfor No DNN associated with the PLMN before changed is deactivated, andfurther in a case that the UE_A 10 is not counting the back-off timerfor the first congestion control for No DNN associated with the PLMNbefore changed, and the back-off timer for the first congestion controlfor No DNN associated with the PLMN is not deactivated, that the UE_A 10can transmit a PDU session establishment request message not using theDNN in the new PLMN. Furthermore, based on this configuration, the UE_10may transmit a PDU session establishment request message not using theDNN.

Next, a second example will be described of the case that the secondPLMN after changed is the equivalent PLMN for the first PLMN beforechanged and the registration area change is involved in changing thePLMN. The UE_A 10 may be so configured, in a case that the UE_A 10, inchanging the PLMN like this, is counting the back-off timer for thefirst congestion control for the specific DNN associated with the PLMNbefore changed, or in a case that the back-off timer for the firstcongestion control for the specific DNN associated with the PLMN beforechanged is deactivated, and further in a case that the UE_A 10 is notcounting the back-off timer for the first congestion control for thespecific DNN associated with the PLMN before changed, and the back-offtimer for the first congestion control for the specific DNN associatedwith the PLMN is not deactivated, that the UE_A 10 can transmit a PDUsession establishment request message using the specific DNN in the newPLMN. Furthermore, based on this configuration, the UE_10 may transmit aPDU session establishment request message using the specific DNN.

Next, a third example will be described of the case that the second PLMNafter changed is the equivalent PLMN for the first PLMN before changedand the registration area change is involved in changing the PLMN. TheUE_A 10 may stop the back-off timer associated with the first congestioncontrol for the specific DNN and/or No DNN in changing the PLMN likethis. Accordingly, the UE_A 10 the UE_A 10 may be configured to transmita PDU session establishment request message using the specific DNNand/or a PDU session establishment request message not using thespecific DNN, in the new PLMN. Furthermore, based on this configuration,the UE_10 may transmit a PDU session establishment request message usingthe specific DNN and/or a PDU session establishment request message notusing the specific DNN.

Although the above description describes that whether the similarprocess is performed regardless of whether the first congestion controlis for the specific DNN or No DNN, or the different process is performedmay be configured in advance based on the information configured for theUE_A 10, or may be determined depending on whether or not the secondPLMN after changed is the equivalent PLMN for the first PLMN beforechanged, the different process may be configured to be performed for thesecond to fourth congestion controls, regardless of the first congestioncontrol. For example, in a case that the second PLMN after changed isnot the equivalent PLMN for the first PLMN before changed, the similarprocess may be applied. In a case that the second PLMN after changed isthe equivalent PLMN for the first PLMN before changed, the differentprocess may be applied.

Furthermore, the UE_A 10 may determine the behavior, based on additionaldetailed conditions, as well as whether or not the second PLMN afterchanged is the equivalent PLMN. For example, the UE_A 10 may beconfigured to perform behaviors different between a case that the secondPLMN after changed is the equivalent PLMN for the first PLMN beforechanged and the registration area is not changed in changing the PLMN,and a case that the second PLMN after changed is the equivalent PLMN forthe first PLMN before changed and the registration area change isinvolved in changing the PLMN.

Note that the behavior of the UE_A 10 performed in each case may be oneof the behaviors in a case that the PLMN is changed described above.

Hereinafter, an example in which the second congestion control isapplied will be described.

For example, a first example will be described of the case that thesecond PLMN after changed is the equivalent PLMN for the first PLMNbefore changed and the registration area is not changed in changing thePLMN. The UE_A 10 may be so configured, in a case that the UE_A 10, inchanging the PLMN like this, is counting the back-off timer associatedwith the second congestion control for the specific S-NSSAI, or theback-off timer associated with the second congestion control for thespecific S-NSSAI is deactivated, that the UE_A 10 does not transmit aPDU session establishment request message using this specific S-NSSAI inthe new PLMN. Accordingly, based on this configuration, the UE_10 may beregulated regarding the transmission of a PDU session establishmentrequest message using this specific S-NSSAI.

A second example will be described of the case that the second PLMNafter changed is the equivalent PLMN for the first PLMN before changedand the registration area is not changed in changing the PLMN. The UE_A10 may be so configured, in a case that the UE_A 10, in changing thePLMN like this, is counting the back-off timer associated with thesecond congestion control for No S-NSSAI, or the back-off timerassociated with the first congestion control for No S-NSSAI isdeactivated, that the UE_A 10 does not transmit a PDU sessionestablishment request message not using the S-NSSAI in the new PLMN.Accordingly, based on this configuration, the UE_10 may be regulatedregarding the transmission of a PDU session establishment requestmessage not using the S-NSSAI.

Next, a first example will be described of the case that the second PLMNafter changed is the equivalent PLMN for the first PLMN before changedand the registration area change is involved in changing the PLMN. TheUE_A 10 may be so configured, in a case that the UE_A 10, in changingthe PLMN like this, is counting the back-off timer for the secondcongestion control for No S-NSSAI associated with the PLMN beforechanged, or in a case that the back-off timer for the second congestioncontrol for No S-NSSAI associated with the PLMN before changed isdeactivated, and further in a case that the UE_A 10 is not counting theback-off timer for the second congestion control for No S-NSSAIassociated with the PLMN after changed, and the back-off timer for thesecond congestion control for No S-NSSAI associated with the PLMN is notdeactivated, that the UE_A 10 can transmit a PDU session establishmentrequest message not using the S-NSSAI in the new PLMN. Furthermore,based on this configuration, the UE_10 may transmit a PDU sessionestablishment request message not using the S-NSSAI.

Next, a second example will be described of the case that the secondPLMN after changed is the equivalent PLMN for the first PLMN beforechanged and the registration area change is involved in changing thePLMN. The UE_A 10 may be so configured, in a case that the UE_A 10, inchanging the PLMN like this, is counting the back-off timer for thesecond congestion control for the specific S-NSSAI associated with thePLMN before changed, or in a case that the back-off timer for the secondcongestion control for the specific S-NSSAI associated with the PLMNbefore changed is deactivated, and further in a case that the UE_A 10 isnot counting the back-off timer for the second congestion control forthe specific S-NSSAI associated with the PLMN before changed, and theback-off timer for the second congestion control for the specificS-NSSAI associated with the PLMN is not deactivated, that the UE_A 10can transmit a PDU session establishment request message using thespecific S-NSSAI in the new PLMN. Furthermore, based on thisconfiguration, the UE_10 may transmit a PDU session establishmentrequest message using the specific S-NSSAI.

Next, a third example will be described of the case that the second PLMNafter changed is the equivalent PLMN for the first PLMN before changedand the registration area change is involved in changing the PLMN. TheUE_A 10 may stop the back-off timer associated with the secondcongestion control for the specific S-NSSAI and/or No S-NSSAI inchanging the PLMN like this. Accordingly, the UE_A 10 the UE_A 10 may beconfigured to be able to transmit a PDU session establishment requestmessage using the specific S-NSSAI and/or a PDU session establishmentrequest message not using the specific S-NSSAI, in the new PLMN.Furthermore, based on this configuration, the UE_10 may transmit a PDUsession establishment request message using the specific S-NSSAI and/ora PDU session establishment request message not using the specificS-NSSAI.

An example of a case that the third congestion control is applied willbe described below.

For example, a first example will be described of the case that thesecond PLMN after changed is the equivalent PLMN for the first PLMNbefore changed and the registration area is not changed in changing thePLMN. The UE_A 10 may be so configured, in a case that the UE_A 10, inchanging the PLMN like this, is counting the back-off timer associatedwith the third congestion control for the specific [S-NSSAI, DNN], orthe back-off timer associated with the third congestion control for thespecific [S-NSSAI, DNN] is deactivated, that the UE_A 10 does nottransmit a PDU session establishment request message using this specific[S-NSSAI, DNN] in the new PLMN. Accordingly, based on thisconfiguration, the UE_10 may be regulated regarding the transmission ofa PDU session establishment request message using this specific[S-NSSAI, DNN].

A second example will be described of the case that the second PLMNafter changed is the equivalent PLMN for the first PLMN before changedand the registration area is not changed in changing the PLMN. The UE_A10 may be so configured, in a case that the UE_A 10, in changing thePLMN like this, is counting the back-off timer associated with the thirdcongestion control for [No S-NSSAI, DNN], or the back-off timerassociated with the third congestion control for [No S-NSSAI, DNN] isdeactivated, that the UE_A 10 does not transmit a PDU sessionestablishment request message for [No S-NSSAI, DNN] in the new PLMN.Accordingly, based on this configuration, the UE_10 may be regulatedregarding the transmission of a PDU session establishment requestmessage for [No S-NSSAI, DNN].

Next, a first example will be described of the case that the second PLMNafter changed is the equivalent PLMN for the first PLMN before changedand the registration area change is involved in changing the PLMN. TheUE_A 10 may be so configured, in a case that the UE_A 10, in changingthe PLMN like this, is counting the back-off timer for the thirdcongestion control for [No S-NSSAI, DNN] associated with the PLMN beforechanged, or in a case that the back-off timer for the third congestioncontrol for [No S-NSSAI, DNN] associated with the PLMN before changed isdeactivated, and further in a case that the UE_A 10 is not counting theback-off timer for the third congestion control for [No S-NSSAI, DNN]associated with the PLMN after changed, and the back-off timer for thethird congestion control for [No S-NSSAI, DNN] associated with the PLMNis not deactivated, that the UE_A 10 can transmit a PDU sessionestablishment request message for [No S-NSSAI, DNN] in the new PLMN.Furthermore, based on this configuration, the UE_10 may transmit a PDUsession establishment request message for [No S-NSSAI, DNN].

Next, a second example will be described of the case that the secondPLMN after changed is the equivalent PLMN for the first PLMN beforechanged and the registration area change is involved in changing thePLMN. The UE_A 10 may be so configured, in a case that the UE_A 10, inchanging the PLMN like this, is counting the back-off timer for thethird congestion control for the specific [S-NSSAI, DNN] associated withthe PLMN before changed, or in a case that the back-off timer for thethird congestion control for the specific [S-NSSAI, DNN] associated withthe PLMN before changed is deactivated, and further in a case that theUE_A 10 is not counting the back-off timer for the third congestioncontrol for the specific [S-NSSAI, DNN] associated with the PLMN afterchanged, and the back-off timer for the third congestion control for thespecific [S-NSSAI, DNN] associated with the PLMN is not deactivated,that the UE_A 10 can transmit a PDU session establishment requestmessage using the specific [S-NSSAI, DNN] in the new PLMN. Furthermore,based on this configuration, the UE_10 may transmit a PDU sessionestablishment request message using the specific [S-NSSAI, DNN].

Next, a third example will be described of the case that the second PLMNafter changed is the equivalent PLMN for the first PLMN before changedand the registration area change is involved in changing the PLMN. TheUE_A 10 may stop the back-off timer associated with third congestioncontrol for the specific [S-NSSAI, DNN] and/or [No S-NSSAI, DNN] inchanging the PLMN like this. Accordingly, the UE_A 10 the UE_A 10 may beconfigured to transmit a PDU session establishment request message usingthe specific [S-NSSAI, DNN] and/or a PDU session establishment requestmessage for [No S-NSSAI, DNN], in the new PLMN. Furthermore, based onthis configuration, the UE_10 may transmit a PDU session establishmentrequest message using the specific [S-NSSAI, DNN] and/or a PDU sessionestablishment request message for [No S-NSSAI, DNN].

Note that in the present embodiment, the back-off timer beingdeactivated may be the back-off timer and/or the congestion controlassociated with the back-off timer transitioning to a deactivated state.Note that the UE_A 10 in a case of receiving the timer value indicatingthe deactivation may deactivate the back-off timer and/or the congestioncontrol associated with the back-off timer.

Here, the back-off timer to be deactivated and/or the congestion controlassociated with the back-off timer may be associated with the congestioncontrol types of 1 to 4. Which congestion control type the back-offtimer to be deactivated and/or the congestion control associated withthe back-off timer is associated with may be similarly determined andrecognized in a case of receiving the back-off timer value.

More specifically, the UE_A 10 may receive the fourteenth identificationinformation indicating that the back-off timer and/or the congestioncontrol associated with the back-off timer is deactivated, and thefifteenth identification information from the NW to deactivate theback-off timer for the congestion control of the type indicated by thefifteenth identification information.

In a state where the back-off timer and/or the congestion control aredeactivated, the application of the congestion control may continueuntil the terminal is turned OFF or the USIM is retrieved. Further, theprocess regulated at this time may be similar to the process regulatedin a case that the count of the back-off timer is performed inaccordance with the type of each congestion control.

Although the processes of the UE_A 10 and NW with the change of the PLMNdescribed above have been associated with the first congestion controland/or the back-off timer for the first congestion control, a similarprocess may be performed for the second congestion control, the thirdcongestion control, and the fourth congestion control. However, the PDUsession establishment request message of which transmission is regulatedor allowed may be a message depending on each type.

In other words, the congestion control and/or the back-off timerassociated with the congestion control may be associated with the PLMNregardless of the type of congestion control.

Alternatively, any congestion control and/or the back-off timerassociated with the congestion control may be configured to beassociated with the PLMN. Thus, the congestion control and/or theback-off timer associated with the congestion control may be configuredto be associated with the PLMN for the first congestion control, thesecond congestion control, and the third congestion control.Alternatively, the congestion control and/or the back-off timerassociated with the congestion control may be configured to beassociated with the PLMN for the first congestion control, the secondcongestion control, and the third congestion control for the No DNN, andthe first congestion control for the specific DNN need may notnecessarily be associated with the PLMN.

Note that the process in a case that each congestion control isassociated with the PLMN, and/or the process relating to the back-offtimer corresponding to each congestion control may be a process in whichthe above-described process for the first congestion control associatedwith the PLMN, and/or the above-described first congestion control inthe description of the process related to the back-off timercorresponding to the first congestion control associated with the PLMNis substituted with each of the second to fourth congestion controltypes.

The process in a case that each congestion control is not associatedwith the PLMN, and/or the process relating to the back-off timercorresponding to each congestion control may be a process in which theabove-described process for the first congestion control not associatedwith the PLMN, and/or the above-described first congestion control inthe description of the process related to the back-off timercorresponding to the first congestion control not associated with thePLMN are substituted with each of the second to fourth congestioncontrol types.

However, as described above, the PDU session establishment requestmessage of which transmission is regulated or allowed may be a messagedepending on each type.

Alternatively, the behavior in a case that the PLMN is changed while thecounting of the back-off timer associated with the second congestioncontrol and/or the third congestion control is running may be performedas described below in addition to the processing described above.

Note that the back-off timer associated with the second congestioncontrol may be a back-off timer for slice-based congestion control, aspreviously described.

Specifically, the sliced-based back-off timer may be a timer associatedwith a specific S-NSSAI and for prohibiting the transmission of an SMrequest message using the specific S-NSSAI. In other words, the UE_A 10may configure such that the SM request message using the specificS-NSSAI is not transmitted during counting the timer.

Furthermore, the UE_A 10 may configure, during counting the timer, suchthat transmission of the SM request message prohibited in the PLMNbefore changed is allowed in the new PLMN, based on the specificconditions described below. Note that the expression that thetransmission of the SM request message prohibited in the PLMN beforechanged is allowed may mean that the transmission of the SM requestmessage using the S-NSSAI the same as the S-NSSAI associated with theback-off timer is allowed.

The slice-based back-off timer may also be a timer associated with noS-NSSAI for prohibiting the transmission of the SM request messagesusing no S-NSSAI. In other words, the UE_A 10 may configure such thatthe SM request message using no S-NSSAI is not transmitted duringcounting the timer. Furthermore, the UE_A 10 may configure, duringcounting the timer, such that transmission of the SM request messageprohibited in the PLMN before changed is allowed in the new PLMN, basedon the specific conditions described below. Note that the expressionthat the transmission of the SM request message prohibited in the PLMNbefore changed is allowed may mean that the transmission of the SMrequest message using no S-NSSAI is allowed.

The back-off timer associated with the third congestion control may be aback-off timer for congestion control for the combination of the S-NSSAIand the DNN, as described above.

Specifically, the back-off timer for congestion control for thecombination of the S-NSSAI and the DNN may be a timer associated withthe combination of the specific S-NSSAI and the specific DNN forprohibiting the transmission of the SM request message using thespecific S-NSSAI and the specific DNN. In other words, the UE_A 10 mayconfigure such that the SM request message using the specific S-NSSAIand the specific DNN is not transmitted during counting the timer.Furthermore, the UE_A 10 may configure, during counting the timer, suchthat transmission of the SM request message prohibited in the PLMNbefore changed is allowed in the new PLMN, based on the specificconditions described below. Note that the expression that thetransmission of the SM request message prohibited in the PLMN beforechanged is allowed may mean that the transmission of the SM requestmessage using the S-NSSAI the same as the S-NSSAI associated with theback-off timer and the DNN the same as the DNN associated with theback-off timer is allowed.

The back-off timer for congestion control for the combination of theS-NSSAI and the DNN may be a timer associated with the combination of noS-NSSAI and the specific DNN for prohibiting the transmission of the SMrequest message using no S-NSSAI and the specific DNN. In other words,the UE_A 10 may configure such that the SM request message including noS-NSSAI and the specific DNN is not transmitted during counting thetimer. Furthermore, the UE_A 10 may configure, during counting thetimer, such that transmission of the SM request message prohibited inthe PLMN before changed is allowed in the new PLMN, based on thespecific conditions described below. Note that the expression that thetransmission of the SM request message prohibited in the PLMN beforechanged is allowed may mean that the transmission of the SM requestmessage using no S-NSSAI and the DNN the same as the DNN associated withthe back-off timer is allowed.

The back-off timer for congestion control for the combination of theS-NSSAI and the DNN may be a timer associated with the combination ofthe specific S-NSSAI and no DNN for prohibiting the transmission of theSM request message using the specific S-NSSAI and no DNN. In otherwords, the UE_A 10 may configure such that the SM request message usingthe specific S-NSSAI and no DNN is not transmitted during counting thetimer. Furthermore, the UE_A 10 may configure, during counting thetimer, such that transmission of the SM request message prohibited inthe PLMN before changed is allowed in the new PLMN, based on thespecific conditions described below. Note that the expression that thetransmission of the SM request message prohibited in the PLMN beforechanged is allowed may mean that the transmission of the SM requestmessage using the S-NSSAI the same as the S-NSSAI associated with theback-off timer and no DNN is allowed.

The back-off timer for congestion control for the combination of theS-NSSAI and the DNN may be a timer associated with the combination of noS-NSSAI and no DNN for prohibiting the transmission of the SM requestmessage using no S-NSSAI and no DNN. In other words, the UE_A 10 mayconfigure such that the SM request message using no S-NSSAI and no DNNis not transmitted during counting the timer. Furthermore, the UE_A 10may configure, during counting the timer, such that transmission of theSM request message prohibited in the PLMN before changed is allowed inthe new PLMN, based on the specific conditions described below. Notethat the expression that the transmission of the SM request messageprohibited in the PLMN before changed is allowed may mean that thetransmission of the SM request message using no S-NSSAI and no DNN isallowed.

Note that in the present embodiment, the expression that the SM requestmessage is transmitted using no S-NSSAI may mean that the SM requestmessage without including the specific S-NSSAI is transmitted. Thenetwork receiving such SM request message may recognize the request as arequest for the default S-NSSAI and/or the default network slice becauseno S-NSSAI is included. Thus, no S-NSSAI may be information indicatingthat S-NSSAI is not included in the SM request message and/orinformation meaning that the default network slice is requested.

Note that in the present embodiment, the expression that the SM requestmessage is transmitted using no DNN may mean that the SM request messagewithout including the specific DNN is transmitted. The network receivingsuch an SM request message may recognize the request as a request forthe default DNN because no DNN is included. Thus, no DNN may beinformation indicating that no S-NSSAI is included in the SM requestmessage and/or information indicating that the default DNN is requested.

Further, the UE_A 10 may start the back-off timer associated with thesecond congestion control, based on the reception of the fifteenthidentification information. Furthermore, the UE_A 10 may configure thefourteenth identification information for the timer value of theback-off timer, based on the reception of the fourteenth identificationinformation. Furthermore, the UE_A 10 may associate the S-NSSAI with theback-off timer in a case that the S-NSSAI is provided in the PDU sessionestablishment procedure. Conversely, the UE_A 10 may associate noS-NSSAI with the back-off timer in a case that S-NSSAI is not providedin the PDU session establishment procedure.

Further, the UE_A 10 may start the back-off timer associated with thethird congestion control, based on the reception of the fifteenthidentification information. Furthermore, the UE_A 10 may configure thefourteenth identification information for the timer value of theback-off timer, based on the reception of the fourteenth identificationinformation. Furthermore, the UE_A 10 may associate the S-NSSAI and theDNN with the back-off timer in a case that the S-NSSAI and the DNN areprovided in the PDU session establishment procedure. Furthermore, theUE_A 10 may associate the S-NSSAI and no DNN with the back-off timer ina case that the S-NSSAI is provided and no DNN is provided in the PDUsession establishment procedure. Furthermore, the UE_A 10 may associateno S-NSSAI and the DNN with the back-off timer in a case that no S-NSSAIis provided and the DNN is provided in the PDU session establishmentprocedure. Furthermore, the UE_A 10 may associate no S-NSSAI and no DNNwith the back-off timer in a case that neither S-NSSAI nor DNN isprovided in the PDU session establishment procedure.

Note that the fourteenth identification information and/or the fifteenthidentification information may be transmitted and/or received with beingincluded in the PDU session establishment reject message that istransmitted and/or received in the PDU session establishment procedure.Furthermore, the fourteenth identification information and/or thefifteenth identification information may be transmitted and/or receivedwith being included in the PDU session reject message that istransmitted and/or received in the PDU session modification procedure.Furthermore, the fourteenth identification information and/or thefifteenth identification information may be transmitted and/or receivedwith being included in the PDU session release command message that istransmitted and/or received in the PDU session release procedure.

The UE_A 10 may be configured to perform any process of first to eighthprocess examples described below in a case of performing the count ofany one or multiple of two examples of the back-off timers for thesecond congestion control and four examples of the back-off timers forthe third congestion control described above.

The first process example will be described below.

Note that in the first process example, the 20th identificationinformation may be an information element indicating whether or not anS-NSSAI-based congestion control is adapted in the current PLMN andother PLMNs than the PLMN. Note that the S-NSSAI-based congestioncontrol may be the second congestion control or the third congestioncontrol.

In this case, the 20th identification information may be capable ofincluding information indicating that the S-NSSAI-based congestioncontrol is adapted in the current PLMN and other PLMNs than the PLMN, orinformation indicating that the S-NSSAI-based congestion control isadapted only in the current PLMN. In other words, the 20thidentification information may be information including the 21stidentification information or the 22nd identification information.

Here, the 21st identification information may be information indicatingthat the S-NSSAI-based congestion control is adapted in the current PLMNand other PLMNs than the PLMN. Furthermore, the 22nd identificationinformation may be information indicating that the S-NSSAI-basedcongestion control is adapted only in the current PLMN.

Furthermore, the 20th identification information may be an informationelement indicating whether or not the counted back-off timer is valid inthe all PLMNs. Note that the back-off timer may be a back-off timer usedfor the S-NSSAI-based congestion control.

In this case, the 20th identification information may be capable ofincluding information indicating that the counted back-off timer isvalid in the all PLMNs, or information indicating that the countedback-off timer is valid only in the current PLMN. In other words, the20th identification information may be information including the 21stidentification information or the 22nd identification information.

Here, the 21st identification information may be information indicatingthat the counted back-off timer is valid in the all PLMNs. Further, the22nd identification information may be information indicating that thecounted back-off timer is valid only in the current PLMN.

Furthermore, the 20th identification information may be an informationelement indicating whether or not the home PLMN is congested. Note thatthe home PLMN being congested may be the slice in the home PLMN beingcongested. Moreover, the home PLMN being congested may be a state inwhich the S-NSSAI-based congestion control is performed in the homePLMN.

In this case, the 20th identification information may be capable ofincluding information indicating that the home PLMN is congested, orinformation indicating that the home PLMN is not congested. In otherwords, the 20th identification information may be information includingthe 21st identification information or the 22nd identificationinformation.

Here, the 21st identification information may be information indicatingthat the home PLMN is congested. Furthermore, the 22nd identificationinformation may be information indicating that the home PLMN is notcongested.

Furthermore, the 20th identification information may be informationindicating whether the S-NSSAI associated with the S-NSSAI-basedcongestion control is the S-NSSAI for the home PLMN or the S-NSSAI for avisited PLMN.

In this case, the 20th identification information may be capable ofincluding information indicating that the S-NSSAI associated with theS-NSSAI-based congestion control is the S-NSSAI for the home PLMN, orinformation indicating that the S-NSSAI associated with the S-NSSAIbased congestion control is the S-NSSAI for the visited PLMN. In otherwords, the 20th identification information may be information includingthe 21st identification information or the 22nd identificationinformation.

Here, the 21st identification information may be information indicatingthat the S-NSSAI associated with the S-NSSAI-based congestion control isthe S-NSSAI for the home PLMN.

Furthermore, the 22nd identification information may be informationindicating that the S-NSSAI associated with the S-NSSAI-based congestioncontrol is the S-NSSAI for the visited PLMN.

Furthermore, in the case of the first process example, the 20thidentification information may be identification information transmittedand/or received in the visited PLMN and not transmitted and/or receivedin the home PLMN.

The process of the UE_A 10, in the first process example, in receivingthe back-off timer in the home PLMN and then moving from the home PLMNto another PLMN will be described.

In other words, the process of the UE_A 10, in the first processexample, moving from the home PLMN to another PLMN while the back-offtimer is running will be described below.

The UE_A 10 in changing the PLMN, in a case that the PLMN before changedis the home PLMN, may continue the regulation for the transmission ofthe SM request message described in each example in a destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

In this way, the UE_A 10 may perform the first process exampleregardless of whether receiving the 20th identification informationdescribed later, in a case of receiving the back-off timer. In otherwords, the UE_A 10 may be configured to perform the first processexample even in a case of not receiving the 20th identificationinformation described later in a case of receiving the back-off timer.In other words, the UE_A 10 may be configured to continue the regulationby the back-off timer received in the home PLMN even after changing thePLMN.

Next, the process, in the first process example, in receiving theback-off timer in the visited PLMN and then moving to another PLMN willbe described. In other words, the process of the UE_A 10, in the firstprocess example, moving from the visited PLMN to another PLMN while theback-off timer is running will be described below.

The UE_A 10 may configure such that in a case that the UE_A 10 inchanging the PLMN receives the 22nd identification information in a caseof receiving the back-off timer, and/or does not receive the 20thidentification information in a case of receiving the back-off timer,the transmission of the SM request message described in each example isallowed in the destination PLMN depending on the counted back-off timer.In other words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is allowed depending on the counted back-off timer.Further, in other words, in this case, in the destination PLMN, the UE_A10 may configure such that the transmission of the SM request messagethat is prohibited in the PLMN before changed described in each exampleis allowed depending on the counted back-off timer.

However, in a case that the UE_A 10 in changing the PLMN receives the21st identification information in a case of receiving the back-offtimer, the UE_A 10 may continue the regulation for the transmission ofthe SM request message described in each example in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the visited PLMN, and the UE_A 10 performs the countof the back-off timer in the PLMN before changed and receives the 20thidentification information configured in the 21st identificationinformation along with the value of the back-off timer, may continue theregulation for the transmission of the SM request message described ineach example depending on the counted back-off timer. In other words, inthis case, in the destination PLMN, the UE_A 10 may configure such thatthe transmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the visited PLMN, and the UE_A 10 performs the countof the back-off timer in the PLMN before changed and receives the 21stidentification information along with the value of the back-off timer,may continue the regulation for the transmission of the SM requestmessage described in each example depending on the counted back-offtimer. In other words, in this case, in the destination PLMN, the UE_A10 may configure such that the transmission of the SM request messagedescribed in each example is prohibited depending on the countedback-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and alsoperforming the count of the back-off timer in the destination PLMN, maycontinue the regulation for the transmission of the SM request messagedescribed in each example depending on the counted back-off timer. Inother words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is prohibited depending on the counted back-off timer.

Next, the second process example will be described.

Note that in the second process example, the 20th identificationinformation may be an information element indicating that theS-NSSAI-based congestion control is adapted in the current PLMN andother PLMNs than the PLMN. Note that the S-NSSAI-based congestioncontrol may be the second congestion control or the third congestioncontrol.

In this case, the 20th identification information may be capable ofincluding information indicating that the S-NSSAI-based congestioncontrol is adapted in the current PLMN and other PLMNs than the PLMN.Furthermore, the 20th identification information may be an informationelement that cannot include the information indicating that theS-NSSAI-based congestion control is adapted only in the current PLMN. Inother words, the 20th identification information may be informationincluding the 21st identification information.

Here, the 21st identification information may be information indicatingthat the S-NSSAI-based congestion control is adapted in the current PLMNand other PLMNs than the PLMN.

Furthermore, the 20th identification information may be an informationelement indicating that the counted back-off timer is valid in the allPLMNs. Note that the back-off timer may be a back-off timer used for theS-NSSAI-based congestion control.

In this case, the 20th identification information may be capable ofincluding information indicating that the counted back-off timer isvalid in the all PLMNs. Furthermore, the 20th identification informationmay be an information element that cannot include the informationindicating that the counted back-off timer is valid only in the currentPLMN. In other words, the 20th identification information may beinformation including the 21st identification information.

Here, the 21st identification information may be information indicatingthat the counted back-off timer is valid in the all PLMNs.

Furthermore, the 20th identification information may be an informationelement indicating that the home PLMN is congested. Note that the homePLMN being congested may be the slice in the home PLMN being congested.Moreover, the home PLMN being congested may be a state in which theS-NSSAI-based congestion control is performed in the home PLMN.

In this case, the 20th identification information may be capable ofincluding information indicating that the home PLMN is congested.Furthermore, the 20th identification information may be an informationelement that cannot include the information indicating that the homePLMN is not congested. In other words, the 20th identificationinformation may be information including the 21st identificationinformation.

Here, the 21st identification information may be information indicatingthat the home PLMN is congested.

Furthermore, the 20th identification information may be informationindicating that the S-NSSAI associated with the S-NSSAI-based congestioncontrol is the S-NSSAI for the home PLMN.

In this case, the 20th identification information may be capable ofincluding the information indicating that the S-NSSAI associated withthe S-NSSAI-based congestion control is the S-NSSAI for the home PLMN.Furthermore, the 20th identification information may be an informationelement that cannot include the information indicating that the S-NSSAIassociated with the S-NSSAI-based congestion control is the S-NSSAI forthe visited PLMN. In other words, the 20th identification informationmay be information including the 21st identification information.

Here, the 21st identification information may be information indicatingthat the S-NSSAI associated with the S-NSSAI-based congestion control isthe S-NSSAI for the home PLMN.

In addition, the 20th identification information may be identificationinformation transmitted and/or received in the visited PLMN and nottransmitted and/or received in the home PLMN.

The process of the UE_A 10, in the second process example, in receivingthe back-off timer in the home PLMN and then moving from the home PLMNto another PLMN will be described. In other words, the process of theUE_A 10, in the second process example, moving from the home PLMN toanother PLMN while the back-off timer is running will be describedbelow.

The UE_A 10 in changing the PLMN, in a case that the PLMN before changedis the home PLMN, may continue the regulation for the transmission ofthe SM request message described in each example in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

In this way, the UE_A 10 may perform the second process exampleregardless of whether receiving the 20th identification informationdescribed later in a case of receiving the back-off timer. In otherwords, the UE_A 10 may be configured to perform the second processexample even in a case of not receiving the 20th identificationinformation described later in a case of receiving the back-off timer.In other words, the UE_A 10 may be configured to continue the regulationby the back-off timer received in the home PLMN even after changing thePLMN.

Next, the process, in the second process example, in receiving theback-off timer in the visited PLMN and then moving to another PLMN willbe described. In other words, the process of the UE_A 10, in the secondprocess example, moving from the visited PLMN to another PLMN while theback-off timer is running will be described below.

The UE_A 10 may configure such that in a case that the UE_A 10, inchanging the PLMN, does not receive the 20th identification informationin a case of receiving the back-off timer, the transmission of the SMrequest message described in each example is allowed in the destinationPLMN depending on the counted back-off timer. In other words, in thiscase, in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isallowed depending on the counted back-off timer. Further, in otherwords, in this case, in the destination PLMN, the UE_A 10 may configuresuch that the transmission of the SM request message that is prohibitedin the PLMN before changed described in each example is alloweddepending on the counted back-off timer.

However, in a case that the UE_A 10 in changing the PLMN receives the21st identification information in a case of receiving the back-offtimer, the UE_A 10 may continue the regulation for the transmission ofthe SM request message described in each example in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the visited PLMN, and the UE_A 10 performs the countof the back-off timer in the PLMN before changed and receives the 20thidentification information and/or the 21st identification informationalong with the value of the back-off timer, may continue the regulationfor the transmission of the SM request message described in each exampledepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and alsoperforming the count of the back-off timer in the destination PLMN, maycontinue the regulation for the transmission of the SM request messagedescribed in each example depending on the counted back-off timer. Inother words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is prohibited depending on the counted back-off timer.

Next, the third process example will be described.

Note that in the third process example, the 20th identificationinformation, the 21st identification information, and the 22ndidentification information may be similar to the pieces ofidentification information described in the first process example.

Furthermore, in the case of the third process example, the 20thidentification information may be identification information that can betransmitted and/or received in both the visited PLMN and the home PLMN.

The process of the UE_A 10, in the third process example, in receivingthe back-off timer in the home PLMN and then moving from the home PLMNto another PLMN will be described. In other words, the process of theUE_A 10, in the third process example, moving from the home PLMN toanother PLMN while the back-off timer is running will be describedbelow.

The UE_A 10 may configure such that in a case that the UE_A 10 changesthe PLMN, in the case that the PLMN before changed is the home PLMN andthe UE_A 10 receives the 22nd identification information in a case ofreceiving the back-off timer, and/or in a case that the UE_A 10 changesthe PLMN, in the case that the PLMN before changed is the home PLMN andthe UE_A 10 does not receive the 20th identification information in acase of receiving the back-off timer, the transmission of the SM requestmessage described in each example is allowed in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isallowed depending on the counted back-off timer. Further, in otherwords, in this case, in the destination PLMN, the UE_A 10 may configuresuch that the transmission of the SM request message that is prohibitedin the PLMN before changed described in each example is alloweddepending on the counted back-off timer.

To be more specific, the UE_A 10 may configure such that in a case thatthe UE_A 10 changes the PLMN, in a case that the PLMN before changed isthe home PLMN and the UE_A 10 does not perform the count of the back-offtimer in the destination PLMN, and further in a case of not receivingthe 20th identification information in a case of receiving the back-offtimer, and/or in a case of receiving the 20th identification informationincluding the 22nd identification information in a case of receiving theback-off timer, and/or in a case of receiving the 22nd identificationinformation in a case of receiving the back-off timer, the transmissionof the SM request message described in each example is allowed in thedestination PLMN depending on the counted back-off timer. In otherwords, in this case, in the destination PLMN, the UE_A 10 may configuresuch that the transmission of the SM request message described in eachexample is allowed depending on the counted back-off timer. Further, inother words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message that isprohibited in the PLMN before changed described in each example isallowed depending on the counted back-off timer.

However, the UE_A 10 in changing the PLMN, in the case that the PLMNbefore changed is the home PLMN and the UE_A 10 receives the 21stidentification information in a case of receiving the back-off timer,may continue the regulation for the transmission of the SM requestmessage described in each example in the destination PLMN depending onthe counted back-off timer. In other words, in this case, in thedestination PLMN, the UE_A 10 may configure such that the transmissionof the SM request message described in each example is prohibiteddepending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the home PLMN, and the UE_A 10 performs the count ofthe back-off timer in the PLMN before changed and receives the 20thidentification information configured in the 21st identificationinformation along with the value of the back-off timer, may continue theregulation for the transmission of the SM request message described ineach example depending on the counted back-off timer. In other words, inthis case, in the destination PLMN, the UE_A 10 may configure such thatthe transmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the home PLMN, and the UE_A 10 performs the count ofthe back-off timer in the PLMN before changed and receives the 21stidentification information along with the value of the back-off timer,may continue the regulation for the transmission of the SM requestmessage described in each example depending on the counted back-offtimer. In other words, in this case, in the destination PLMN, the UE_A10 may configure such that the transmission of the SM request messagedescribed in each example is prohibited depending on the countedback-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the home PLMN, and the UE_A 10 performs the count ofthe back-off timer in the PLMN before changed and also performs thecount of the back-off timer in the destination PLMN, may continue theregulation for the transmission of the SM request message described ineach example depending on the counted back-off timer. In other words, inthis case, in the destination PLMN, the UE_A 10 may configure such thatthe transmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Next, the process, in the third process example, in receiving theback-off timer in the visited PLMN and then moving to another PLMN willbe described. In other words, the process of the UE_A 10, in the thirdprocess example, moving from the visited PLMN to another PLMN while theback-off timer is running will be described below.

The UE_A 10 may configure such that in a case that the UE_A 10 does notreceive the 20th identification information in a case of receiving theback-off timer, and/or the UE_A 10, in changing the PLMN, receives the22nd identification information in a case of receiving the back-offtimer, the transmission of the SM request message described in eachexample is allowed in the destination PLMN depending on the countedback-off timer. In other words, in this case, in the destination PLMN,the UE_A 10 may configure such that the transmission of the SM requestmessage described in each example is allowed depending on the countedback-off timer. Further, in other words, in this case, in thedestination PLMN, the UE_A 10 may configure such that the transmissionof the SM request message that is prohibited in the PLMN before changeddescribed in each example is allowed depending on the counted back-offtimer.

However, in a case that the UE_A 10 in changing the PLMN receives the21st identification information in a case of receiving the back-offtimer, the UE_A 10 may continue the regulation for the transmission ofthe SM request message described in each example in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and receivingthe 20th identification information configured in the 21stidentification information along with the value of the back-off timer,may continue the regulation for the transmission of the SM requestmessage described in each example depending on the counted back-offtimer. In other words, in this case, in the destination PLMN, the UE_A10 may configure such that the transmission of the SM request messagedescribed in each example is prohibited depending on the countedback-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and receivingthe 21st identification information along with the value of the back-offtimer, may continue the regulation for the transmission of the SMrequest message described in each example depending on the countedback-off timer. In other words, in this case, in the destination PLMN,the UE_A 10 may configure such that the transmission of the SM requestmessage described in each example is prohibited depending on the countedback-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and alsoperforming the count of the back-off timer in the destination PLMN, maycontinue the regulation for the transmission of the SM request messagedescribed in each example depending on the counted back-off timer. Inother words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is prohibited depending on the counted back-off timer.

Next, the fourth process example will be described.

Note that in the fourth process example, the 20th identificationinformation, the 21st identification information, and the 22ndidentification information may be similar to the identificationinformation described in the first process example.

Furthermore, in the case of the fourth process example, the 20thidentification information may be identification information that can betransmitted and/or received in the visited PLMN and the home PLMN.

The process of the UE_A 10, in the fourth process example, in receivingthe back-off timer in the home PLMN and then moving from the home PLMNto another PLMN will be described. In other words, the process of theUE_A 10, in the fourth process example, moving from the home PLMN toanother PLMN while the back-off timer is running will be describedbelow.

The UE_A 10 may configure such that in a case that the UE_A 10 changesthe PLMN, in the case that the PLMN before changed is the home PLMN andthe UE_A 10 receives the 22nd identification information in a case ofreceiving the back-off timer, the transmission of the SM request messagedescribed in each example is allowed in the destination PLMN dependingon the counted back-off timer. In other words, in this case, in thedestination PLMN, the UE_A 10 may configure such that the transmissionof the SM request message described in each example is allowed dependingon the counted back-off timer. Further, in other words, in this case, inthe destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message that is prohibited in the PLMNbefore changed described in each example is allowed depending on thecounted back-off timer.

To be more specific, the UE_A 10 may configure such that in a case thatthe UE_A 10 changes the PLMN, in the case that the PLMN before changedis the home PLMN and the UE_A 10 does not perform the count of theback-off timer in the destination PLMN, and further in a case ofreceiving the 20th identification information including the 22ndidentification information in a case of receiving the back-off timer,and/or in a case of receiving the 22nd identification information in acase of receiving the back-off timer, the transmission of the SM requestmessage described in each example is allowed in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isallowed depending on the counted back-off timer. Further, in otherwords, in this case, in the destination PLMN, the UE_A 10 may configuresuch that the transmission of the SM request message that is prohibitedin the PLMN before changed described in each example is alloweddepending on the counted back-off timer.

However, in a case that the UE_A 10 changes the PLMN, in the case thatthe PLMN before changed is the home PLMN and the UE_A 10 receives the21st identification information in a case of receiving the back-offtimer, and/or in a case that the UE_A 10 changes the PLMN, in the casethat the PLMN before changed is the home PLMN and the UE_A 10 does notreceive the 20th identification information in a case of receiving theback-off timer, the UE_A 10 may continue regulation for the transmissionof the SM request message described in each example in the destinationPLMN depending on the counted back-off timer. In other words, in thiscase, in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Next, the process, in the fourth process example, in receiving theback-off timer in the visited PLMN and then moving to another PLMN willbe described. In other words, the process of the UE_A 10, in the fourthprocess example, moving from the visited PLMN to another PLMN while theback-off timer is running will be described below.

The UE_A 10 may configure such that in a case that the UE_A 10 does notreceive the 20th identification information in a case of receiving theback-off timer, and/or the UE_A 10, in changing the PLMN, receives the22nd identification information in a case of receiving the back-offtimer, the transmission of the SM request message described in eachexample is allowed in the destination PLMN depending on the countedback-off timer. In other words, in this case, in the destination PLMN,the UE_A 10 may configure such that the transmission of the SM requestmessage described in each example is allowed depending on the countedback-off timer. Further, in other words, in this case, in thedestination PLMN, the UE_A 10 may configure such that the transmissionof the SM request message that is prohibited in the PLMN before changed,described in each example, is allowed depending on the counted back-offtimer.

However, in a case that the UE_A 10 in changing the PLMN receives the21st identification information in a case of receiving the back-offtimer, the UE_A 10 may continue the regulation for the transmission ofthe SM request message described in each example in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and receivingthe 20th identification information configured in the 21stidentification information along with the value of the back-off timer,may continue the regulation for the transmission of the SM requestmessage described in each example depending on the counted back-offtimer. In other words, in this case, in the destination PLMN, the UE_A10 may configure such that the transmission of the SM request messagedescribed in each example is prohibited depending on the countedback-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and receivingthe 21st identification information along with the value of the back-offtimer, may continue the regulation for the transmission of the SMrequest message described in each example depending on the countedback-off timer. In other words, in this case, in the destination PLMN,the UE_A 10 may configure such that the transmission of the SM requestmessage described in each example is prohibited depending on the countedback-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and alsoperforming the count of the back-off timer in the destination PLMN, maycontinue the regulation for the transmission of the SM request messagedescribed in each example depending on the counted back-off timer. Inother words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is prohibited depending on the counted back-off timer.

Next, the fifth process example will be described.

Note that in the fifth process example, the 20th identificationinformation and the 21st identification information may be similar tothe pieces of identification information described in the second processexample.

Furthermore, in the case of the fifth process example, the 20thidentification information may be identification information that can betransmitted and/or received in the visited PLMN and the home PLMN.

The process of the UE_A 10, in the fifth process example, in receivingthe back-off timer in the home PLMN and then moving from the home PLMNto another PLMN will be described. In other words, the process of theUE_A 10, in the fifth process example, moving from the home PLMN toanother PLMN while the back-off timer is running will be describedbelow.

The UE_A 10 may configure such that in a case that the UE_A 10 changesthe PLMN, in the case that the PLMN before changed is the home PLMN andthe UE_A 10 does not receive the 20th identification information in acase of receiving the back-off timer, and/or in a case that the UE_A 10changes the PLMN, in the case that the PLMN before changed is the homePLMN and the UE_A 10 receives the 20th identification information notincluding the 21st identification information in a case of receiving theback-off timer, the transmission of the SM request message described ineach example is allowed in the destination PLMN depending on the countedback-off timer. In other words, in this case, in the destination PLMN,the UE_A 10 may configure such that the transmission of the SM requestmessage described in each example is allowed depending on the countedback-off timer. Further, in other words, in this case, in thedestination PLMN, the UE_A 10 may configure such that the transmissionof the SM request message that is prohibited in the PLMN before changeddescribed in each example is allowed depending on the counted back-offtimer.

To be more specific, the UE_A 10 may configure such that in a case thatthe UE_A 10 changes the PLMN, in the case that the PLMN before changedis the home PLMN and the UE_A 10 does not perform the count of theback-off timer in the destination PLMN, and further in a case of notreceiving the 20th identification information in a case of receiving theback-off timer, and/or in a case of receiving the 20th identificationinformation not including the 21st identification information in a caseof receiving the back-off timer, the transmission of the SM requestmessage described in each example is allowed in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isallowed depending on the counted back-off timer. Further, in otherwords, in this case, in the destination PLMN, the UE_A 10 may configuresuch that the transmission of the SM request message that is prohibitedin the PLMN before changed described in each example is alloweddepending on the counted back-off timer.

However, the UE_A 10 in changing the PLMN, in the case that the PLMNbefore changed is the home PLMN and the UE_A 10 receives the 21stidentification information in a case of receiving the back-off timer,may continue the regulation for the transmission of the SM requestmessage described in each example in the destination PLMN depending onthe counted back-off timer. In other words, in this case, in thedestination PLMN, the UE_A 10 may configure such that the transmissionof the SM request message described in each example is prohibiteddepending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the home PLMN, and the UE_A 10 performs the count ofthe back-off timer in the PLMN before changed and receives the 20thidentification information and/or the 21st identification informationalong with the value of the back-off timer, may continue the regulationfor the transmission of the SM request message described in each exampledepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the home PLMN, and the UE_A 10 performs the count ofthe back-off timer in the PLMN before changed and also performs thecount of the back-off timer in the destination PLMN, may continue theregulation for the transmission of the SM request message described ineach example depending on the counted back-off timer. In other words, inthis case, in the destination PLMN, the UE_A 10 may configure such thatthe transmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Next, the process, in the fifth process example, in receiving theback-off timer in the visited PLMN and then moving to another PLMN willbe described. In other words, the process of the UE_A 10, in the fifthprocess example, moving from the visited PLMN to another PLMN while theback-off timer is running will be described below.

The UE_A 10 may configure such that in a case that the UE_A 10 changesthe PLMN, in the case that the UE_A 10 does not receive the 20thidentification information in a case of receiving the back-off timer,and/or in a case that the UE_A 10 changes, in the case that the UE_A 10receives the 20th identification information not including the 21stidentification information in a case of receiving the back-off timer,the transmission of the SM request message described in each example isallowed in the destination PLMN depending on the counted back-off timer.In other words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is allowed depending on the counted back-off timer.Further, in other words, in this case, in the destination PLMN, the UE_A10 may configure such that the transmission of the SM request messagethat is prohibited in the PLMN before changed described in each exampleis allowed depending on the counted back-off timer.

However, in a case that the UE_A 10 in changing the PLMN receives the21st identification information in a case of receiving the back-offtimer, the UE_A 10 may continue the regulation for the transmission ofthe SM request message described in each example in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and receivingthe 20th identification information and/or the 21st identificationinformation along with the value of the back-off timer, may continue theregulation for the transmission of the SM request message described ineach example depending on the counted back-off timer. In other words, inthis case, in the destination PLMN, the UE_A 10 may configure such thatthe transmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and alsoperforming the count of the back-off timer in the destination PLMN, maycontinue the regulation for the transmission of the SM request messagedescribed in each example depending on the counted back-off timer. Inother words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is prohibited depending on the counted back-off timer.

Next, the sixth process example will be described.

Note that in the sixth process example, the 20th identificationinformation, the 21st identification information, and the 22ndidentification information may be similar to the identificationinformation described in the first process example.

Furthermore, in the case of the sixth process example, the 20thidentification information may be identification information transmittedand/or received in the visited PLMN and not transmitted and/or receivedin the home PLMN.

The process of the UE_A 10, in the sixth process example, in receivingthe back-off timer in the home PLMN and then moving from the home PLMNto another PLMN will be described. In other words, the process of theUE_A 10, in the sixth process example, moving from the home PLMN toanother PLMN while the back-off timer is running will be describedbelow.

The UE_A 10 may configure such that in a case that the UE_A 10 changesthe PLMN, in the case that the PLMN before changed is the home PLMN, thetransmission of the SM request message described in each example isallowed in the destination PLMN depending on the counted back-off timer.In other words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is allowed depending on the counted back-off timer.Further, in other words, in this case, in the destination PLMN, the UE_A10 may configure such that the transmission of the SM request messagethat is prohibited in the PLMN before changed described in each exampleis allowed depending on the counted back-off timer.

To be more specific, the UE_A 10 may configure such that in a case thatthe UE_A 10 changes the PLMN, in the case that the PLMN before changedis the home PLMN and the UE_A 10 does not perform the count of theback-off timer in the destination PLMN, the transmission of the SMrequest message described in each example is allowed in the destinationPLMN depending on the counted back-off timer. In other words, in thiscase, in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isallowed depending on the counted back-off timer. Further, in otherwords, in this case, in the destination PLMN, the UE_A 10 may configuresuch that the transmission of the SM request message that is prohibitedin the PLMN before changed described in each example is alloweddepending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the home PLMN, and the UE_A 10 performs the count ofthe back-off timer in the PLMN before changed and also performs thecount of the back-off timer in the destination PLMN, may continue theregulation for the transmission of the SM request message described ineach example depending on the counted back-off timer. In other words, inthis case, in the destination PLMN, the UE_A 10 may configure such thatthe transmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Next, the process, in the sixth process example, in receiving theback-off timer in the visited PLMN and then moving to another PLMN willbe described. In other words, the process of the UE_A 10, in the sixthprocess example, moving from the visited PLMN to another PLMN while theback-off timer is running will be described below.

The UE_A 10 may configure such that in a case that the UE_A 10 inchanging the PLMN receives the 22nd identification information in a caseof receiving the back-off timer, and/or does not receive the 20thidentification information in a case of receiving the back-off timer,the transmission of the SM request message described in each example isallowed in the destination PLMN depending on the counted back-off timer.In other words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is allowed depending on the counted back-off timer.Further, in other words, in this case, in the destination PLMN, the UE_A10 may configure such that the transmission of the SM request messagethat is prohibited in the PLMN before changed described in each exampleis allowed depending on the counted back-off timer.

However, in a case that the UE_A 10 in changing the PLMN receives the21st identification information in a case of receiving the back-offtimer, the UE_A 10 may continue the regulation for the transmission ofthe SM request message described in each example in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the visited PLMN, and the UE_A 10 performs the countof the back-off timer in the PLMN before changed and receives the 20thidentification information configured in the 21st identificationinformation along with the value of the back-off timer, may continue theregulation for the transmission of the SM request message described ineach example depending on the counted back-off timer. In other words, inthis case, in the destination PLMN, the UE_A 10 may configure such thatthe transmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the visited PLMN, and the UE_A 10 performs the countof the back-off timer in the PLMN before changed and receives the 21stidentification information along with the value of the back-off timer,may continue the regulation for the transmission of the SM requestmessage described in each example depending on the counted back-offtimer. In other words, in this case, in the destination PLMN, the UE_A10 may configure such that the transmission of the SM request messagedescribed in each example is prohibited depending on the countedback-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and alsoperforming the count of the back-off timer in the destination PLMN, maycontinue the regulation for the transmission of the SM request messagedescribed in each example depending on the counted back-off timer. Inother words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is prohibited depending on the counted back-off timer.

Next, the seventh process example will be described.

Note that in the seventh process example, the 20th identificationinformation and the 21st identification information may be similar tothe identification information described in the second process example.

Furthermore, in the case of the seventh process example, the 20thidentification information may be identification information transmittedand/or received in the visited PLMN and not transmitted and/or receivedin the home PLMN.

The process of the UE_A 10, in the seventh process example, in receivingthe back-off timer in the home PLMN and then moving from the home PLMNto another PLMN will be described. In other words, the process of theUE_A 10, in the seventh process example, moving from the home PLMN toanother PLMN while the back-off timer is running will be describedbelow.

The UE_A 10 may configure such that in a case that the UE_A 10 changesthe PLMN, in the case that the PLMN before changed is the home PLMN, thetransmission of the SM request message described in each example isallowed in the destination PLMN depending on the counted back-off timer.In other words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is allowed depending on the counted back-off timer.Further, in other words, in this case, in the destination PLMN, the UE_A10 may configure such that the transmission of the SM request messagethat is prohibited in the PLMN before changed described in each exampleis allowed depending on the counted back-off timer.

To be more specific, the UE_A 10 may configure such that in a case thatthe UE_A 10 changes the PLMN, in the case that the PLMN before changedis the home PLMN and the UE_A 10 does not perform the count of theback-off timer in the destination PLMN, the transmission of the SMrequest message described in each example is allowed in the destinationPLMN depending on the counted back-off timer. In other words, in thiscase, in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isallowed depending on the counted back-off timer. Further, in otherwords, in this case, in the destination PLMN, the UE_A 10 may configuresuch that the transmission of the SM request message that is prohibitedin the PLMN before changed described in each example is alloweddepending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the home PLMN, and the UE_A 10 performs the count ofthe back-off timer in the PLMN before changed and also performs thecount of the back-off timer in the destination PLMN, may continue theregulation for the transmission of the SM request message described ineach example depending on the counted back-off timer. In other words, inthis case, in the destination PLMN, the UE_A 10 may configure such thatthe transmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Next, the process, in the seventh process example, in receiving theback-off timer in the visited PLMN and then moving to another PLMN willbe described. In other words, the process of the UE_A 10, in the seventhprocess example, moving from the visited PLMN to another PLMN while theback-off timer is running will be described below.

The UE_A 10 may configure such that in a case that the UE_A 10 does notreceive the 20th identification information in a case of receiving theback-off timer, the transmission of the SM request message described ineach example is allowed in the destination PLMN depending on the countedback-off timer. In other words, in this case, in the destination PLMN,the UE_A 10 may configure such that the transmission of the SM requestmessage described in each example is allowed depending on the countedback-off timer. Further, in other words, in this case, in thedestination PLMN, the UE_A 10 may configure such that the transmissionof the SM request message that is prohibited in the PLMN before changeddescribed in each example is allowed depending on the counted back-offtimer.

However, in a case that the UE_A 10 in changing the PLMN receives the21st identification information in a case of receiving the back-offtimer, the UE_A 10 may continue the regulation for the transmission ofthe SM request message described in each example in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case that the PLMNbefore changed is the visited PLMN, and the UE_A 10 performs the countof the back-off timer in the PLMN before changed and receives the 20thidentification information and/or the 21st identification informationalong with the value of the back-off timer, may continue the regulationfor the transmission of the SM request message described in each exampledepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and alsoperforming the count of the back-off timer in the destination PLMN, maycontinue the regulation for the transmission of the SM request messagedescribed in each example depending on the counted back-off timer. Inother words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is prohibited depending on the counted back-off timer.

Next, the eighth process example will be described.

Note that in the eighth process example, the 20th identificationinformation and the 21st identification information may be similar tothe identification information described in the second process example.

Furthermore, in the case of the eighth process example, the 20thidentification information may be identification information that can betransmitted and/or received in the visited PLMN and the home PLMN.

The process of the UE_A 10, in the eighth process example, in receivingthe back-off timer in the home PLMN and then moving from the home PLMNto another PLMN will be described. In other words, the process of theUE_A 10, in the eighth process example, moving from the home PLMN toanother PLMN while the back-off timer is running will be describedbelow.

The UE_A 10 in changing the PLMN, in a case that the PLMN before changedis the home PLMN, may continue the regulation for the transmission ofthe SM request message described in each example in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

In this way, the UE_A 10 may perform the eighth process exampleregardless of whether receiving the 20th identification informationdescribed later in a case of receiving the back-off timer. In otherwords, the UE_A 10 may be configured to perform the eighth processexample even in a case of not receiving the 20th identificationinformation described later in a case of receiving the back-off timer.In other words, the UE_A 10 may be configured to continue the regulationby the back-off timer received in the home PLMN even after changing thePLMN.

Next, the process, in the eighth process example, in receiving theback-off timer in the visited PLMN and then moving to another PLMN willbe described. In other words, the process of the UE_A 10, in the eighthprocess example, moving from the visited PLMN to another PLMN while theback-off timer is running will be described below.

The UE_A 10 may configure such that in a case that the UE_A 10, inchanging the PLMN, does not receive the 20th identification informationin a case of receiving the back-off timer, the transmission of the SMrequest message described in each example is allowed in the destinationPLMN depending on the counted back-off timer. In other words, in thiscase, in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isallowed depending on the counted back-off timer. Further, in otherwords, in this case, in the destination PLMN, the UE_A 10 may configuresuch that the transmission of the SM request message that is prohibitedin the PLMN before changed described in each example is alloweddepending on the counted back-off timer.

However, in a case that the UE_A 10 in changing the PLMN receives the21st identification information in a case of receiving the back-offtimer, the UE_A 10 may continue the regulation for the transmission ofthe SM request message described in each example in the destination PLMNdepending on the counted back-off timer. In other words, in this case,in the destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and receivingthe 20th identification information and/or the 21st identificationinformation along with the value of the back-off timer, may continue theregulation for the transmission of the SM request message described ineach example depending on the counted back-off timer. In other words, inthis case, in the destination PLMN, the UE_A 10 may configure such thatthe transmission of the SM request message described in each example isprohibited depending on the counted back-off timer.

Furthermore, the UE_A 10 in changing the PLMN, in a case of performingthe count of the back-off timer in the PLMN before changed and alsoperforming the count of the back-off timer in the destination PLMN, maycontinue the regulation for the transmission of the SM request messagedescribed in each example depending on the counted back-off timer. Inother words, in this case, in the destination PLMN, the UE_A 10 mayconfigure such that the transmission of the SM request message describedin each example is prohibited depending on the counted back-off timer.

Note that in the all processes described above, the UE_A 10 mayconfigure such that in a case that UE_A 10 in changing the PLMN does notsatisfy the above conditions, the transmission of the SM request messagedescribed in each example is allowed in the destination PLMN dependingon the counted back-off timer. In other words, in this case, in thedestination PLMN, the UE_A 10 may configure such that the transmissionof the SM request message described in each example is allowed dependingon the counted back-off timer. Further, in other words, in this case, inthe destination PLMN, the UE_A 10 may configure such that thetransmission of the SM request message that is prohibited in the PLMNbefore changed described in each example is allowed depending on thecounted back-off timer.

In the description in the present embodiment, the expression that the NWtransmits to the UE_A 10 may mean that the AMF or the SMF transmits tothe UE_A 10, and the expression that the UE_A 10 transmits to the NW maymean that the UE_A 10 transmits to the AMF or the SMF. Furthermore, theexpression that the UE_A 10 receives from the NW may mean that the AMFor the SMF receives from to the UE_A 10, and the expression that theUE_A 10 receives from the NW may mean that the UE_A 10 receives from theAMF or the SMF.

2. Modified Examples

A program running on an apparatus according to the present invention mayserve as a program that controls a Central Processing Unit (CPU) and thelike to cause a computer to operate in such a manner as to realize thefunctions of the above-described embodiment according to the presentinvention. Programs or information handled by the programs aretemporarily stored in a volatile memory such as a Random Access Memory(RAM), a non-volatile memory such as a flash memory, a Hard Disk Drive(HDD), or another storage device system.

Note that a program for realizing such functions of the embodimentaccording to the present invention may be recorded on acomputer-readable recording medium. It may be implemented by causing acomputer system to read and execute the program recorded on thisrecording medium. It is assumed that the “computer system” refers to acomputer system built into the apparatuses, and the computer systemincludes an operating system and hardware components such as aperipheral device. Furthermore, the “computer-readable recording medium”may be any of a semiconductor recording medium, an optical recordingmedium, a magnetic recording medium, a medium dynamically retaining theprogram for a short time, or any other computer readable recordingmedium.

Furthermore, each functional block or various characteristics of theapparatuses used in the above-described embodiment may be implemented orperformed on an electric circuit, for example, an integrated circuit ormultiple integrated circuits. An electric circuit designed to performthe functions described in the present specification may include ageneral purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), or other programmable logic devices, discrete gatesor transistor logic, discrete hardware components, or a combinationthereof. The general-purpose processor may be a microprocessor, or maybe a processor of a known type, a controller, a micro-controller, or astate machine instead. The above-mentioned electric circuit may includea digital circuit, or may include an analog circuit. Furthermore, in acase that a circuit integration technology that replaces the presentintegrated circuit appears with advances in semiconductor technology,one or more aspects of the present invention can also use a newintegrated circuit based on the technology.

Note that the invention of the present patent application is not limitedto the above-described embodiments. In the embodiment, apparatuses havebeen described as an example, but the invention of the presentapplication is not limited to these apparatuses, and is applicable to aterminal apparatus or a communication apparatus of a fixed-type or astationary-type electronic apparatus installed indoors or outdoors, forexample, an AV apparatus, a kitchen apparatus, a cleaning or washingmachine, an air-conditioning apparatus, office equipment, a vendingmachine, and other household apparatuses.

Although, the embodiments of the present invention have been describedin detail above referring to the drawings, the specific configuration isnot limited to the embodiments and includes, for example, design changeswithin the scope not depart from the gist of the present invention.Furthermore, in the present invention, various modifications arepossible within the scope of claims, and embodiments that are made bysuitably combining technical means disclosed according to the differentembodiments are also included in the technical scope of the presentinvention. Furthermore, a configuration in which elements described inthe respective embodiments and having mutually similar effects, aresubstituted for one another is also included.

1.-3. (canceled)
 4. A User Equipment (UE) comprising: transmission andreception circuitry configured to receive, from a control device, aProtocol Data Unit (PDU) session establishment reject message in a PDUsession establishment procedure; and a controller configured to start aback-off timer with a back-off timer value, in a case that firstinformation and the back-off timer value are included in the PDU sessionestablishment reject message, and in a case that a Single Network SliceSelection Assistance information (S-NSSAI) and a Data Network Name (DNN)combination were provided during the PDU session establishmentprocedure, wherein the first information is a cause value indicatinginsufficient resources for specific slice and DNN, the back-off timer isa timer for S-NSSAI based congestion control, the back-off timer isassociated with the S-NSSAI and the DNN combination that the UE providedduring the PDU session establishment procedure, and in a case that thefirst information and second information indicating that the back-offtimer is applied in registered Public Land Mobile Network (PLMN) areincluded in the PDU session establishment reject message, another PDUsession establishment request message or a PDU session modificationrequest message for the S-NSSAI and DNN combination is not sent in aregistered PLMN while the back-off timer is running.
 5. The UE accordingto claim 4, wherein in a case that the first information and the secondinformation indicating that the back-off timer is applied in all PLMNsare included in the PDU session establishment reject message, anotherPDU session establishment request message or a PDU session modificationrequest message for the S-NSSAI and DNN combination is not sent in allPLMNs while the back-off timer is running.
 6. The UE according to claim4, wherein in a case that the first information and the secondinformation indicating that the back-off timer is applied in all PLMNsare included in the PDU session establishment reject message, and upon aPLMN change, another PDU session establishment request message or a PDUsession modification request message for the S-NSSAI and DNN combinationis not sent while the back-off timer is running.
 7. A communicationmethod performed by a User Equipment (UE), the communication methodcomprising: receiving, from a control device, a Protocol Data Unit (PDU)session establishment reject message in a PDU session establishmentprocedure; and starting a back-off timer with a back-off timer value, ina case that first information and the back-off timer value are includedin the PDU session establishment reject message, and in a case that aSingle Network Slice Selection Assistance information (S-NSSAI) and aData Network Name (DNN) combination were provided during the PDU sessionestablishment procedure, wherein the first information is a cause valueindicating insufficient resources for specific slice and DNN, theback-off timer is a timer for S-NSSAI based congestion control, theback-off timer is associated with the S-NSSAI and the DNN combinationthat the UE provided during the PDU session establishment procedure, andin a case that the first information and second information indicatingthat the back-off timer is applied in registered Public Land MobileNetwork (PLMN) are included in the PDU session establishment rejectmessage, another PDU session establishment request message or a PDUsession modification request message for the S-NSSAI and DNN combinationis not sent in a registered PLMN while the back-off timer is running.